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Page 1: Silicone Gel Breast Implants - Dr Marshall Murdochdrmjmurdoch.co.za/wp/wp-content/uploads/2015/01/Silicone... · 2015-01-05 · 6 Silicone gel breast implants: Report of the IRG,

Silicone Gel Breast ImplantsThe Report of the Independent Review Group

GIR Independent Review Group

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Silicone GelBreast Implants

The Report of theIndependent Review Group

July 1998© Crown CopyrightISBN 1 85839 909 2

Silicone Gel Breast Implants, The Report of the IndependentReview Group has been prepared for publication byJill Rogers Associates, Cambridge

Design by Information Design Workshop, LondonPrinted by Soloprint, Cambridgeshire

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3Silicone gel breast implants: Report of the IRG, 1998

Foreword 4Summary 51. Introduction: Why have an

Independent Review Group? 81.1 The reason for the Independent

Review Group 81.2 How the IRG went about its work 9

2. The Report and How it is Organised 102.1 Target readership for the report 102.2 Integrated report and Website 102.3 Addressing concerns and making

recommendations 10

3. Silicone Gel Breast Implants 113.1 How common are silicone gel

breast implants? 113.2 What is a breast implant? 123.3 Exposure to silicone 12

4. Health Risks: The Evidence 144.1 The evidence: introduction 144.2 Safety 14

5. Local Effects 155.1 Capsular contracture 155.2 Infection 155.3 Gel bleed 165.4 Rupture 16

6. Distant and Systemic Effects 176.1 Immunological and pathological effects 176.2 Long-term systemic effects 21

6.2.1 The role of epidemiological studies to assess risk 21

6.2.2 Association or causation 226.2.3 Relative and absolute risk 226.2.4 Specific connective tissue diseases 226.2.5 Non-specific systemic illness 23

6.3 Neurological disorders 236.4 Hormonal disorders 236.5 Effects on children of women with

breast implants 246.6 Silicone toxicity 246.7 Cancer 25

Contents

7. Overall Conclusions from the Scientific Evidence 26

8. Responding to Concerns: Conclusions and Recommendations 27

8.1 Provision of adequate information beforeconsultation 27

8.2 Provision of adequate information at the consultation 28

8.3 Post-operative care 288.4 Follow-up 288.5 Consent for the operation 308.6 Regulation of private clinics 308.7 National Breast Implant Registry 318.8 Adverse incidents 328.9 Future research 32

Annexes 331. Members of the Independent Review

Group and Advisors to the Independent Review Group 33

2. Oral Evidence considered by the Independent Review Group 34

References 35

Glossary 36

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Foreword To the Chief Medical Officer

I am pleased to present the report of theIndependent Review Group. We were charged byyou with the responsibility to ‘review the evidencerelating to the possible health risks associated withsilicone gel breast implants, to examine the issues relatingto pre-operative patient information and to report to youon our conclusions’.

We are aware of the importance of the outcomes ofour task for women who have had, and who willhave, silicone gel breast implants, for their families,for health care professionals involved in their care,for manufacturers, lawyers, and others who areconcerned with the issues surrounding the use ofsilicone gel breast implants.

Our members were selected for their independentviews, their knowledge and understanding of theissues and lack of any vested interest in theconclusions reached. We have met frequently, haveconsidered an extensive literature, and have takenevidence from expert witnesses, including patients,patient groups, clinicians, lawyers, manufacturersand scientists. This evidence has been gathered fromexperts both in the United Kingdom and overseas.

We have taken a fresh look at the existing andemerging scientific evidence for a link betweensilicone gel breast implants and effects on health. In the process of this, we have been conscious of theneed to examine carefully the causes of ill health in a number of women with implants.

We have made recommendations which willaddress the concerns of women with silicone gelbreast implants, encourage further research intoimportant areas, and enable clinicians,manufacturers, scientists and the general public to work together to ensure the highest levels ofconfidence in the production, use and long termeffects of silicone gel breast implants.

Professor Roger D Sturrock MD FRCPChairman of the Independent Review GroupThe McLeod/Arthritis Research Campaign Professorof Rheumatology, University of Glasgow

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5Silicone gel breast implants: Report of the IRG, 1998

Summary The Independent Review Group (IRG) wasestablished in response to concerns expressed bywomen in relation to silicone gel breast implants.

The Chief Medical Officer, at the request of theMinister of Health, Baroness Jay, set up the IRG withthe remit:

‘to review the evidence relating to the possible healthrisks associated with silicone gel breast implants, toexamine the issues relating to pre-operative patientinformation, and to report to the Chief Medical Officeron its conclusions.’

In fulfilling the remit, the IRG has taken a fresh lookat the existing and emerging scientific evidence for alink between silicone gel breast implants and effectson health. Additionally, the IRG gathered evidenceon the quality and quantity of information routinelyprovided to women about to undergo breastimplantation. The IRG:

■ reviewed the existing reports and evidence

■ identified and considered new evidence

■ considered the possible existence of a new,undefined syndrome

■ considered the range of risks associated withsilicone gel breast implants

■ examined whether patient information issatisfactory

■ considered how good clinical practice can beassured.

The IRG considered evidence from a number ofsources, including:

■ oral evidence from representatives/nominees ofpatient groups, lawyers, researchers, physicians,plastic surgeons, industry and the NationalBreast Implant Registry

■ written evidence from interested parties,including women with breast implants, replies torequests for information, and additionalinformation from those who gave oral evidence

■ plaintiff and defence submissions to the scientificpanel appointed to review the scientific merits ofevidence presented in litigation in the UnitedStates

■ unpublished scientific information, legalsubmissions, letters from women with siliconegel breast implants, Internet and press articles

■ scientific publications

■ data provided by manufacturers.

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6 Silicone gel breast implants: Report of the IRG, 1998

The IRG considered immense amounts of complexevidence and reached a number of conclusions.

1. There is no histopathological or conclusiveimmunological evidence for an abnormal immuneresponse to silicone from breast implants in tissue.

2. There is no epidemiological evidence for any linkbetween silicone gel breast implants and anyestablished connective tissue disease. If there is arisk of connective tissue disease, it is too small to bequantified. The IRG cannot justify recommendingfurther epidemiological studies to investigate thishypothesis.

3. Good evidence for the existence of atypicalconnective tissue disease or undefined conditions,such as ‘silicone poisoning’ is lacking. It is possiblethat other conditions such as low grade chronicinfection may account for some of the non-specificillnesses noted in some women with silicone gelbreast implants.

4. The overall biological response to silicone isconsistent with conventional forms of response toforeign materials, rather than an unusual toxicreaction.

5. There is no evidence that children of women withbreast implants are at increased risk of connectivetissue disease.

6. The IRG recognised that there were issues such asthe precise incidence of rupture where the scientificdata were incomplete so that rigorous conclusionscould not be drawn.

The IRG recognised that:

■ there are physical and psychological benefits ofbreast implantation for many women

■ there are a number of complications such ascapsular contracture and gel bleed associatedwith breast implantation

■ information provided to women to assist them inmaking informed decisions about whether toproceed with breast implant surgery is frequentlyinadequate, in terms of both quality and quantity

■ there is a need to extend the principles of goodclinical practice and clinical audit across someareas of the private sector

■ there is a need to improve scientific quality in anumber of areas of research relating to aspects ofsilicone gel breast implants.

To address these areas of concern, the IRG makes anumber of recommendations.

Recommendation 1

The IRG recommends that all patients undergoingcosmetic breast augmentation surgery should be ableto obtain, free of charge, from a designated body,comprehensive information about the benefits and risksof such surgery. This should be accompanied by achecklist of topics (see Figure 2) which should becovered when the possibility of an operation isdiscussed.

Recommendation 2

The IRG recommends that advertisements in all mediapromoting breast implant surgery should include astatement indicating that anyone contemplating thistype of surgery can obtain information about theoperation and its risks from a designated body.

Recommendation 3

The IRG recommends that all women undergoing orproposing to undergo cosmetic breast augmentationsurgery should be offered the following:

1. an initial appointment with the surgeon carrying outthe operation

2. an opportunity to discuss the checklist of issues withthat surgeon. Figure 2 contains a list of issues thatshould be included in any checklist

3. information on the likely financial implications ofbreast implant surgery including the fact that furthertreatment and expenditure may be necessary at sometime in the future. These costs may include not onlyinitial consultations and operation but also regularfollow-up, screening for rupture if this is thought to haveoccurred, explantation and reimplantation

4. a ‘cooling off’ period of several days between theinitial consultation with the surgeon and the operation

5. a guarantee that any deposit or payment for theoperation will be fully refunded if for any reason thewoman changes her mind, even at the very lastmoment, and cancels the operation

6. an assurance that they will not come into directcontact with a representative of a particularmanufacturer prior to agreeing to surgery.

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Recommendation 4

The IRG recommends that a specific consent form bedeveloped which incorporates, as an integral part, thechecklist of issues (see Figure 2). The consent formshould confirm that the different types of implantavailable have been discussed with the surgeon and thetype agreed, and that all subjects on the checklist havebeen discussed to the woman’s satisfaction along withany other concerns that the woman wishes to address.This consent form should be signed by the surgeon andthe woman. One copy should be kept by the surgeon inthe notes, and one copy kept by the woman.

Recommendation 5

The IRG recommends that measures should beintroduced to ensure that proper standards of care areimplemented in clinics carrying out breast implantationwithin the private sector. In particular, a qualityassurance system, including the sending of a routineletter to the woman’s GP, and clinical audit proceduresshould be standard practice within such clinics.

Recommendation 6

The IRG recommends that prospective registration ofdetails of each breast implant and explant operation onthe National Breast Implant Registry should becompulsory.

In addition all women should be given the opportunityto participate in long term follow-up projects with thefull understanding that they may be contacted in thefuture to provide information to facilitate research.

It should be explained to the woman that the Registrywill be used to gather accurate data on the outcomesassociated with silicone gel breast implants, includingthe incidence of rupture.

Recommendation 7

The IRG recommends that all clinicians should reportbreast implant related adverse incidents to the MedicalDevices Agency Adverse Incident Centre. The MDAshould provide guidance to clinicians on whichincidents should be reported.

Recommendation 8

The IRG recommends that a small steering group beset up to prioritise, plan and monitor the followingprogramme of research. Priorities should include:

■ research into the true incidence of rupture

■ research into the aetiology of symptoms exhibitedby a number of women who have had implants, inparticular to elucidate the role, if any, of sub-clinicalinfection.

The IRG recommends that the steering group shouldalso consider the need to validate the results of otherstudies, such as those by Ellis et al.

The IRG concluded that the publications of Tenenbaumet al., and Smalley et al., were not conclusive and areopen to legitimate scientific criticisms. However, inview of concerns expressed by women’s groups, theIRG recommends that there would be scientific merit indetermining whether the results of these studies canbe reproduced by independent laboratories.

Recommendation 9

Although there is currently no justification for routineregular breast investigation to detect rupture, the IRGrecommends that this subject should be kept underreview and the decision revisited in the light of possiblenew information and technical advances relating toimaging techniques used in the detection of rupture.

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8 Silicone gel breast implants: Report of the IRG, 1998

1Introduction:Why have anIndependentReviewGroup?

1.1 The reason for the Independent Review Group

The Independent Review Group was established inresponse to concerns expressed by women inrelation to silicone gel breast implants.

Because of these concerns the Minister of Health,Baroness Jay, asked the Chief Medical Officer toundertake a review of the use of silicone gel breastimplants in the United Kingdom. The Chief MedicalOfficer addressed this request by setting up anIndependent Review Group (IRG) with the remit:

‘to review the evidence relating to the possible health risksassociated with silicone gel breast implants, to examinethe issues relating to pre-operative patient information,and to report to the Chief Medical Officer on itsconclusions.’

The members of the IRG were selected for theirindependence, their knowledge and understandingof the issues, and their lack of vested interest in theconclusions reached. Members are listed at Annex 1.

The IRG set out to respond to concerns that siliconegel breast implants may be the underlying cause ofmedical problems which can severely affect thequality of women’s lives, and that women perceivedthat their symptoms were not always takenseriously. Some women also complained that theywere inadequately informed about the possible risksand complications of breast implants before theyhad surgery and were therefore unable to make aproperly informed choice.

Although some men, for gender alteration purposes,undergo breast implantation, the vast majority ofbreast implant procedures are carried out in women.In this report we refer, therefore, solely to women.

The IRG has taken a fresh look at the existing andemerging scientific evidence for a link betweensilicone gel breast implants and effects on health. Inso doing the IRG identified two key questions:

■ why are some women ill?

■ what information do women considering breastimplant surgery need and how best can thatinformation be presented?

To address these questions the IRG:

■ reviewed the existing reports and evidence

■ identified and considered new evidence

■ considered the possible existence of a new,undefined syndrome

■ considered the range of risks associated withsilicone gel breast implants

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9Silicone gel breast implants: Report of the IRG, 1998

■ examined whether patient information issatisfactory

■ considered how good clinical practice can beassured.

The IRG specifically addressed the problemsassociated with silicone gel breast implants.Silicone injections, hydrogel filled implants orother filling materials such as oil or saline wereexcluded from the remit given to the IRG.

GlossaryWhile every effort has been made to make thetext explicit, a glossary of terms is provided atthe end of the report. The terms are highlightedin the text by the letter G.

1.2 How the IRG went about its work

The IRG considered evidence from a number ofsources, including:

■ oral evidence from representatives/nominees ofpatient groups, lawyers, researchers, physicians,plastic surgeons, industry and the NationalBreast Implant Registry

■ written evidence from interested parties,including women with breast implants, replies torequests for information, and additionalinformation from those who gave oral evidence

■ plaintiff and defence submissions to the scientificpanel appointed to review the scientific merits ofevidence presented in litigation in the UnitedStates

■ unpublished scientific information, legalsubmissions, letters from women with siliconegel breast implants, Internet and press articles

■ scientific publications

■ data provided by manufacturers.

The IRG appointed a number of advisors who wereasked to consider specific information on behalf ofthe IRG. The names of the advisors are listed atAnnex 1. The names of those who gave oralevidence are provided at Annex 2.

In considering the range of evidence, the IRGexamined all relevant scientific data. Great emphasiswas placed on considering the scientific quality ofeach study in addition to the conclusions drawn.

The IRG noted the large number of scientific papersand other material published in the past five yearson the possible link between silicone gel breastimplants and the development of connective tissuedisease. The 1994 review by the Medical Devices

Agency (Gott and Tinkler, 1994) commented on thepoor scientific quality of some of the papersreviewed and on how this limited the conclusionsthat could be drawn from much of the research. Thisview was repeated by scientific and clinicalwitnesses to the IRG concerning some paperspublished in the past five years.

The IRG also expressed concern that some paperswere not subject to adequate peer review. Similarly,a number of seemingly authoritative reviews of theliterature were highlyselective in the papersthey included, thusappearing to supportcertain hypotheses whichwere not supported bythe evidence as a whole.

This introduced theadditional problem thatthe public and mediawould not be aware of the lack of scientific rigourand could be persuaded and alarmed by the resultsof what was, in fact, poor science and selectivereporting.

During the past five years there have been sustainedcampaigns by interested parties to put across theirpoints of view in the media. The amount ofpublished, or electronically distributed materialadvocating a particular point of view is huge. Whilesuch parties are entitled to campaign, it is notsurprising that the evidence they cite is chosen tosupport their case, rather than for its scientificquality. It needs to be remembered that this is notthe same process as drawing unbiased conclusionsafter evaluating all the relevant scientific andmedical evidence.

Peer reviewed scienceThe judgement of scientificinvestigations byindependent experts toensure that the conclusionsrecorded are justified bythe methods used and theresults obtained.

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2The Reportand How itis Organised

2.1 Target readership for the report

This report is intended for a variety of groups whohave particular interests in silicone gel breastimplants:

■ women considering, or who have had, breastimplants, and their families

■ plastic surgeons and other clinicians in the NHSand independent sectors

■ manufacturers

■ lawyers

■ policy makers in health care

■ scientists.

2.2 Integrated report and Website

The IRG considered immense amounts of complexevidence. This report necessarily contains analysisof the evidence together with the IRG’s key findingsand recommendations. Some readers will wish toaccess further information or more detaileddiscussion of certain aspects. The IRG has thereforeprovided a dedicated Website which contains thisinformation. The IRG’s aim has been to providehighly accessible information about its work. It isthe IRG’s intention that the Website be updatedregularly to reflect the latest evidence about siliconegel breast implants. The Website also contains thereferences to the literature considered by the IRG.This published report contains only thosereferences relevant to the IRG’s key findings andrecommendations.

Website address www.silicone-review.gov.uk

2.3 Addressing concerns and making recommendations

The IRG has considered the scientific evidence onthe subject of silicone gel breast implants and areasof particular concern among women and the public,such as the possibility of silicone poisoning, chronicfatigue syndrome, non-specific pain, effects onchildren of women with breast implants, andimmune responses to silicone. After considering theevidence, the IRG has made recommendations withthe specific aims of:

■ addressing the concerns of women with siliconegel breast implants

■ encouraging further research into important areasof concern

■ enabling clinicians to give women consideringimplants the most up-to-date advice aboutpossible associated problems

■ enabling clinicians, manufacturers, scientists andwomen to work in partnership to ensure thehighest levels of confidence in the production,use and monitoring of silicone gel breastimplants.

In preparing this report, the IRG has consideredcarefully a wide range of evidence from individualwomen, patient representative groups, plasticsurgeons, scientists, epidemiologists,immunologists, pathologists, lawyers andmanufacturers of silicone gel breast implants.

This report presents the IRG’s conclusions from theevidence and sets out recommendations to helpensure that women have access to reliableinformation and are enabled to make informedchoices about silicone gel breast implants; thatsurgeons make relevant information readilyavailable; and that data are collected on an ongoingbasis so that the health effects of silicone gel breastimplants can be monitored.

W

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3SiliconeGel BreastImplants

What is silicone?It is important to understand the differences between silicon, silica and silicone because of theimplications in the interpretation of scientific studies.

■ Silicon is the second most abundant element, making up about 28% of the earth’s crust.

■ Silica is a three dimensional network of silicon dioxide and is most commonly encountered as sand.

■ Silicones are not found naturally. They are man-made polymers used in a wide variety of products as fluids, gels and rubbers. They have a high degree of chemicalinertness, thermal stability and resistance to oxidation. Modified silica is bound into siliconerubbers to provide strength.

See Website What is silicone? for further information about silicones and their measurement.www.silicone-review.gov.uk/silicone

Throughout this report the word silicone will be used for polydimethylsiloxaneG (PDMS) polymersincluding their low molecular weight components.

3.1 How common are silicone gel breast implants?

Breast enlargement is the most common cosmeticprocedure performed on women in the UnitedKingdom. It is estimated that around 8,000 suchoperations are performed each year. It is difficult toobtain accurate figures because a large number ofunrecorded operations are carried out in theindependent sector. Four groups of women seekbreast enlargement:

■ women who are dissatisfied with the size of their breasts

■ women with congenital absence of one or two breasts

■ women who have had normal breast developmentbut the breast size has decreased followingpregnancy or with increasing age

■ women who have undergone mastectomy fortreatment of breast cancer or because of a strongfamily history of breast cancer.

Silicone gel breast implants have been available sincethe early 1960s and have been the subject ofinvestigation and monitoring since the mid-1980s. Thetime line, shown at Figure 1, outlines the history ofsilicone gel breast implants.

It is worth noting that in 1992 the USA’s Food andDrug Administration limited the use of silicone gelbreast implants to clinical trials. The increase in US

W

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12 Silicone gel breast implants: Report of the IRG, 1998

3.2 What is a breast implant?

Silicone gel breast implants are made of an outershell of silicone elastomer filled with silicone gel.The composition of the shell is important. Therehave been three generations of implant since theywere made available in the 1960s. The time line,shown at Figure 1, indicates the periods of use ofthese three generations, although there has beensome overlap.

1st generation implants: were made with a thicksilicone shell. They had a smooth surface and werefilled with silicone gel, which is a mixture of siliconesolid and fluid. These implants are associated withsignificant gel bleedG from the implant and capsularcontractureG, that is shrinkage of scar tissue, but arebelieved to have a low rupture rate. These implantswere manufactured from the 1960s and weresuperseded during the mid-1970s.

2nd generation implants: were made with a thinsilicone shell. They had a smooth surface and werefilled with silicone gel. The shell was reduced inthickness in an unsuccessful attempt to decrease theamount of capsular contracture. The gel bleed wassimilar to the 1st generation implants. It is nowwidely accepted that 2nd generation implants aremore susceptible to rupture. They weremanufactured from the 1970s to the late-1980s.

3rd generation implants: are made with a thickershell of silicone, incorporating a barrier layer. Theyhave a textured surface and are filled with siliconegel. The composition of the shell acts as a barrier tominimise gel bleed, the textured surface decreasesthe incidence of capsular contracture. The rupture

rate of these implants is believed to be low but thereare few relevant studies. The gel bleed andcontracture rates are lower than with earlierimplants. They have been manufactured since themid-1980s.

See Website for list of tests expected before asilicone gel breast implant comes onto themarket.www.silicone-review.gov.uk/testing

3.3 Exposure to silicone

It is essential to consider the issue of silicone gelbreast implants in the context of the widespreadexposure to silicones in the environment generally.Silicone is used in both personal and domesticproducts, including cleaning solvents, handcreams,hair and skin products, and antiperspirants. Siliconefrom these sources is absorbed primarily throughthe skin.

Silicone is used in food processing and packagingincluding canning and pre-prepared meals, babies’teats and dummies. Silicone from these sources isabsorbed primarily through the gastro-intestinaltract.

Silicone is also incorporated in some medicines andmedical devices. For example, silicone oil iscommonly used as a lubricant in syringes. Peoplewith insulin dependent diabetes are thereforeexposed to small but regular doses of silicone oil,resulting in a large, cumulative exposure to siliconeover a period of time. Liquid silicone is injected intothe eye during surgery to treat retinal detachment.

See Website Exposure to Silicone for a chartwhich shows the uses, absorption and molecularweights of silicones.www.silicone-review.gov.uk/silicone

litigation that followed led the manufacturers toreach a commercial decision to minimise thepotential costs of litigation by offering a globalsettlement without admitting liability.

In the 1990s a number of countries, including theUnited Kingdom, Canada, the USA and France,carried out systematic reviewsG focusing on thepossible health implications of silicone gel breastimplants. The time line at Figure 1 summarises theoutcomes of these reviews.

See Website for details on history andconclusions from systematic reviews.www.silicone-review.gov.uk/history

W

W

W

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13Silicone gel breast implants: Report of the IRG, 1998

1960

1970

1980

1990

1st generation implants• Thick silicone shell (smooth) • High rate of gel bleed

Silicone gel breast implant invented by plastic surgeons,Cronin and Gerow in early 1960s

Dow Corning developed them into a commercial product.Other manufacturers introduced silicone gel breast implantsin late 1960s

2nd generation implants• Thin silicone shell (smooth)• High rate of gel bleed

Late 1980s, suggested from animal studies that silicone gelbreast implants may cause cancer. Investigated by the UKCommittee on Carcinogenicity who concluded this was causedby a mechanism only relevant to these test animals.

3rd generation implants• Thick silicone shell (textured)• Low rate of gel bleed

Polyurethane foam covering some implants found todegrade in extreme laboratory conditions. Released achemical known to cause cancer in animals, but notpossible to demonstrate this breakdown in humans. Theseimplants withdrawn by manufacturers. Subsequent workestablished that this breakdown can occur in animals andhumans.

In USA, Food and Drug Administration (FDA) requested thesubmission of pre-market approval applications bymanufacturers.

1991 FDA advisory panel recommended manufacturersshould collect additional data on silicone gel breastimplants.

1992 FDA called for voluntary moritorium on use ofsilicone gel breast implants until panel reviewed newinformation. FDA restricted silicone gel breast implants toclinical trials.In UK, Independent Expert Advisory Group (IEAG)established to review information on connective tissuedisease. • found no evidence for an increase in connective tissuedisease• recommended a voluntary Registry of patients.Canadian Independent Advisory Committee concluded thatthere was insufficient evidence for increases in specificdiseases but recognised the need for further research.

1993 National Breast Implant Registry establishedfollowing recommendation by IEAG.

1994 IEAG updated their review; found no reason tochange earlier conclusions.

1996 French Ministry of Health published report from theAgence Nationale pour le Développement de l'EvaluationMedicale. Agreed with earlier UK report.

1997 Independent Review Group established by ChiefMedical Officer, Department of Health at request ofMinister of Health, Baroness Jay.

Figure 1 Three Generations of Silicone Gel Breast Implants

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4Health Risks:The Evidence

4.1 The evidence: introduction

The IRG considered the concerns expressed bywomen relating to possible health risks associatedwith silicone gel breast implants such as gel bleed,capsular contracture, rupture, and infection.

The IRG examined evidence relating to:

■ local effects, that is those which depend on thesilicone gel being present and which occur at thesite of the implant (see Section 5)

■ tissue responses to the presence of silicone (seeSection 6.1)

■ systemic health effects, that is those which do notrequire the silicone gel to be present and whichoccur at sites at a distance from the implant (seeSection 6)

■ the possible effects of silicone gel breast implantson the health of children of women with implants(see Section 6.5)

4.2 Safety

Before considering the detail of the evidence, it isimportant to understand the concept of ‘safety’ inthe context of the scientific evidence relating tosilicone gel breast implants.

The IRG has been asked by its remit to go furtherthan previous UK reviews (Tinkler et al., 1993; Gottand Tinkler, 1994) and to interpret the evidence inrelation to the safety of silicone gel breast implants:to answer the question, are they safe?

However, safety is not a simple concept. It is widelyaccepted by lawyers, ethicists, doctors andregulators to mean freedom from an undue risk ofharm. The word ‘undue’ is critical. It is impossibleto guarantee that any given set of conditions can becompletely free from any possibility of harm: safetyis not an absolute concept. This is particularly so inmedical practice, where deliberate invasiveprocedures carry a risk to health.

It follows therefore that any decision about medicalintervention is a calculated risk, taken inpartnership by the surgeon and the individual, withthe aim of improving the overall circumstances forthe individual. Balancing risks and benefits makessafety a difficult concept to define in any givensituation and, consequently, it is important toconsider ‘safety’ carefully in the context ofindividual circumstances.

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5LocalEffects

5.1 Capsular contracture

The body puts a wall of scar tissue (fibrous capsuleG)around any implanted foreign material and breastimplants are no exception. Scar tissue shrinks, butthe extent of shrinkage varies from person to personand even from breast to breast. This shrinkage, orcapsular contracture, is noticeable to the woman asan apparent hardening of the breast.

With the older smooth surface implants (1st and 2ndgeneration) noticeable capsular contracture occurredin 40% to 60% of implantations. When implants witha textured surface were introduced in the mid-1980s(3rd generation), the reported rate of capsularcontracture fell to around 10% with these implants.

The type of filling used in the implant has not beenshown to have any effect on the incidence ofcontracture. Other factors, such as subclinicalhaematomaG, shrinkage of the surgical pocket orsubclinical infection with organisms such asStaphylococcus epidermidisG, a bacterium normallyfound on the skin, have also been implicated aspossible causes of capsular contracture.

5.2 Infection

The IRG considered the published evidence relatingto the risk of infection from silicone gel breastimplants. It is important to recognise that the intro-duction into the body of any foreign material such asa hip replacement, intravenous catheter, prostheticheart valve, or silicone implant constitutes a risk ofintroduction of bacteria from the patient’s own skin.

The IRG concluded that the possible influence ofinfection on capsular contracture is not proven.Capsular contracture may, however, be exacerbatedby bacterial infection.

Chronic low grade infection may occur with anysurgical implant. Such infection, at any site in thebody, may be associated with a number of symptomsincluding tiredness, weakness, intermittent febrileperiods and muscle aches and pains. There is a needfor more scientific research into this area todetermine how frequently low grade infection occursin women with breast implants and whether thiscontributes to the symptoms complained of by somewomen.

See Website for the details of the studiesreviewed.www.silicone-review.gov.uk/infection

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5.3 Gel bleed

The term gel bleed describes the diffusion of smallmolecules of liquid components of silicone gelthrough the intact shell of the implant. There is noagreed method of measuring gel bleed and this,therefore, limits its accurate quantification.However, these small molecules of silicone compriseless than 1% of the gel. Gel bleed occurs from allbreast implants; the concern is whether the materialthat bleeds causes illness.

These small molecules are handled by the body inexactly the same way as small silicone moleculesfrom other sources, (see Section 3.3).

See Website for further information about gel bleed.www.silicone-review.gov.uk/gel-bleed

5.4 Rupture

Rupture means the development of a split or hole inthe shell of a breast implant. The causes of rupturemay include:

■ deterioration of the implant shell with time - themost common cause

■ undetected damage at the time of operation

■ a shell weakness due to a flaw introduced duringmanufacture

■ trauma to the breast, such as damage from a seatbelt in a traffic accident, or external (closed)capsulotomyG (disruption of the fibrous capsule).

The effects of a rupture may be local and/orregional. There are reports of silicone gel havingmigrated to distant parts of the body such as thearm or trunk, but these are rare.

Local effects of a rupture

With a silicone gel filled implant there may be novery dramatic change in the breast because if theshell ruptures, the gel is often still contained withinthe body’s fibrous capsule (intracapsular rupture).There may, however, be some slight change in shapeor firmness of the breast.

Regional effects of a rupture

If there is a spread of gel through the ruptured shellbeyond the fibrous capsule (extracapsular spread),the rupture will be more obvious with a change inthe shape of the implant and possibly a reduction insize due to extrusion of gel beyond the breast area.

In the vast majority of extracapsular ruptures the gelis still in the region of the original pocket and can beremoved when the ruptured implant is removed.

In a small number of cases the gel has been foundin breast tissue, the muscles under the breast, thearmpit, the axillary lymph nodesG in the armpit, orrarely around the nerves to the arm (brachial plexusG)in the depths of the armpit. In rare cases this mayrequire removal of part of the breast and muscletissue.

Gel outside the capsule can cause someinflammatory reaction with the development oflumps that can be felt. If the gel does move out ofthe breast area there may have been some severephysical trauma to account for this, such ascompression from a seat belt in a car accident or aclosed capsulotomy.

Detection of a rupture by imaging techniques

Intracapsular rupture can be difficult or impossibleto detect by current imaging techniques(mammography, ultrasound and magneticresonance imaging). Often it is only discovered atoperation. However, these imaging techniquescontinue to be developed and evaluated. Bycontrast, extracapsular rupture is often easier todetect by imaging techniques.

Rupture rates

There is little information on the overall rupture rateof breast implants. Breast implants have a finite lifeand inevitably some will rupture. There is littleinformation on rupture or the relationship betweenrupture, time, and indeed, the generation ofimplant. The available estimates of rupture rates arederived mainly from studies using a highly selectedsample of implants. These studies are furthercomplicated by their use of different criteria indefining rupture, for example some include gelbleed within the definition of rupture.

The difficulties of establishing the rate of rupture arecompounded by the use of imaging techniqueswhich in a percentage of cases fail to detect rupturesor incorrectly identify intact implants as ruptured.

See Website for details of rupture rateswww.silicone-review.gov.uk/ruptureW

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6Distant andSystemicEffects

6.1 Immunological and pathological effects

The possibility that silicone gel breast implants maylead to an autoimmune reactionG in women has been amajor cause of concern for several years and acentral focus of the controversy over breastimplants. It was therefore a subject that the IRGexplored in some depth. The IRG has no doubt thatsome women who have had a silicone gel breastimplant are indeed suffering serious symptoms. Thequestion is whether these symptoms are attributableto silicone gel breast implants or to some othercause. Therefore, one of the principal questionsconsidered by the IRG was: Do silicone gel breastimplants lead to the development of an autoimmunedisorder? In this section of the report, this question isconsidered in some detail.

The body has two basic ways of reacting to infectionor foreign materials; these are:

■ inflammation

■ immune reactions.

The nature of the inflammatory response to siliconesis the same as would be expected with any otherforeign material. If a prolonged inflammatoryreaction occurs, fibrous tissue forms to isolate thesite of the injury. Although evidence for an immunereaction to silicone has been reported previously,earlier reports concluded that the evidence wasweak at best. The most recent studies on immunereactions and silicone implants have beenconsidered by the IRG, and the conclusions aregiven later in this report. Immune reactions maylead to the formation of antibodiesG and to thegeneration of reactive T-lymphocytesG (a type of whiteblood cell). The IRG has therefore examined reportsclaiming that antibodies or specifically reactive T-lymphocytes are found in women with siliconeimplants.

It has also been suggested that women with siliconeimplants may develop immune responses againsttheir own tissues - autoimmune disorders, forexample, rheumatoid arthritis, and other connectivetissue diseases. These disorders are characterised bythe presence of antibodies to particular componentsof the patient’s own tissues (autoantibodies) and byspecifically autoreactive T-lymphocytes. The IRGtherefore set out to investigate the evidence for thesechanges. The possible mechanisms through whichan autoimmune reaction might occur have beenextensively reviewed. The most prominent recentadvocates of this theory have been Professors

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Radford Shanklin and Robert Garry whose viewshave been cited particularly by patient groups. Thisevidence was therefore examined in detail.

Professor Shanklin presented two forms of evidenceto the IRG to demonstrate that there is an immunereaction in women with silicone gel breast implants.

1. He provided pathological slides of capsular tissuetaken from women with breast implants. Hepointed out a pathological feature in these slides,which he referred to as vasculitis (inflammationof the blood vessel wall). This is an indicator of animmunological component in a tissue response.

2. He described immunological studies he hadcarried out, using blood samples taken fromimplanted women with symptoms of disease.These claimed to show activation of T-lymphocytes, which is a marker for an immuneeffect. Further evidence from Professor Garry,indicating the presence of anti-polymerantibodies in the blood of women with implants,was also cited as evidence of an immune effect.

Professor Shanklin used these same forms ofevidence to support his further hypothesis thatsilicones escaping from the implant into the tissuesare broken down to silica and that both silicone andsilica are implicated in the immune reaction seen.

■ He pointed to the crystalline appearance ofcertain features in the tissue slides he provided asevidence for the presence of crystalline silica.

■ He presented evidence which suggested to himthat lymphocyte activation occurs in the presenceof silicone as well as silica.

He suggested that the presence of crystalline silicawould be an important factor, since it can inducesilicosis, which has autoimmune features.

In examining the evidence for this hypothesis, theIRG had the assistance of two immunologists andthree histopathologists with relevant experience.The immunologists reviewed evidence from thepublished immunological studies to ascertain whatimmune responses were encountered in womenwith implants. The pathologists considered thepathological changes in tissues from women withbreast implants supplied by Professor Shanklin.They looked, in particular, at whether there was animmune component in the response and theycarried out studies to establish whether silica waspresent in the tissue samples supplied.

In addition, published evidence was examined forthe presence of autoantibodiesG or genetic markers forautoimmune disease in groups of women withimplants. These latter studies provide an indication

of whether autoimmune effects are operating in thegroups studied.

Epidemiological studies, which are discussed inSection 6.2, provide further insight into this aspectof the subject. Published studies of the incidence ofdisease in women with silicone gel breast implantswere reviewed to see whether there was acorrelation between the presence of implants andthe occurrence of rheumatological diseases orsymptoms.

The IRG arrived at nine conclusions in relation toquestions relevant to the hypothesis presented.

1. What pathological responses are associatedwith the presence of silicones in the tissues?

After considering the pathological slides suppliedby Professor Shanklin, the IRG concluded thatsilicone gel breast implants, like other surgicalimplants, are associated with a typical localinflammatory response to the foreign material andthat implants are associated with local fibrosis andthe formation of a membrane between the implantand the body.

The foreign material may occasionally be seen insites other than the breast, particularly the regionaldraining lymph nodes. If overt rupture of theimplant occurs and the silicone material escapes,clearly the possibility arises that a more substantialamount of silicone could accumulate elsewhere inthe body. The extent of gel bleed and the likelihoodof rupture depend primarily on factors related to theimplant (see Section 5.4). A local inflammatoryresponse is also likely to occur at the site of siliconeaccumulation. The consequences of this will dependon the site at which the silicone accumulates and theamount of material present.

See Website for details of the histopathologyreview and samples examined.www.silicone-review.gov.uk/pathology

2. Does silicone break down to silica in thetissues?

The IRG commissioned scientific tests to examinethe claim that silica was present in tissue samplesprovided by Professor Shanklin. The investigatinglaboratory demonstrated the presence of silicone inProfessor Shanklin’s sections, but no silica waspresent in the samples examined. The IRG also

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heard evidence that conversion of silicone to silica isnot possible under the conditions prevailing in thebody.

See Website for details of the scientific testscommissioned by the IRG.www.silicone-review.gov.uk/path-test

3. Do the silicones used in breast implantsprovoke antibody responses against silicones ortheir biological breakdown products?

The IRG concluded that the evidence in the scientificliterature does not suggest that silicones themselvesprovoke antibody responses. Outside the body, thephysical conditions necessary to cause breakdownof silicone polymers are extreme. Such conditions donot occur within the body. In addition, there is nopublished evidence that any identified biologicalbreakdown products of silicone are capable ofinducing an immune response.

4. Does exposure to silicones lead to antibodyresponses to other body substances absorbed to thesilicones?

Experimental animal work indicates that self (andforeign) proteins absorbed to silicone polymers caninduce an antibody response and that silicones maysometimes have a modest adjuvantG effect onantibody production. There is thus evidence fornormal immune reactions occurring in response tocombinations of silicone and protein. There is noevidence, however, that the response can causetissue damage.

5. Do silicones provoke an antibody response topartially polymerised polyacrylamide?

Professor Garry discussed his findings, presented ina recent paper (Tenenbaum et al., 1997) with the IRG.His findings suggested that antibodies specific forpartially polymerised polyacrylamide are seen morefrequently in women with breast implants withsevere symptoms than in women with mild or nosymptoms. The IRG concluded that this study is notconclusive, that the work is subject to legitimatecriticism and that further studies would be neededto determine whether the findings are reproducible.The chemical structure of polyacrylamide isunrelated to that of silicone and no rationale wasput forward to explain why cross-reactivity mightoccur; nor was any cross-reactivity reported,

although this should have been readilydemonstrable. Given this situation, independentconfirmation of this work would be essential beforethe IRG could accept any conclusions drawn from it.

6. Does exposure to silicone lead to theprovocation of a lymphocytic response?

T-lymphocytes are a particular type of white bloodcell that play a crucial role in immune responses andtheir proliferation indicates that such a response hasoccurred. Recent papers (Smalley, Shanklin et al.,1995-7) demonstrated proliferation of T-lymphocytes in blood samples taken from patientswith silicone gel breast implants when they werecultured in the presence of silica. This work wasused to support the suggestion that there is abreakdown of silicones to silica in the body and thatthe silica (which is known to produce immuneeffects) induces an autoimmune process. The workwas poorly controlled and the findings werereported in a way that made them difficult tointerpret. The IRG considered that this work was sodeficient that valid conclusions could not be drawn.

Another recent study (Ellis et al., 1997) showedproliferation of lymphocytes in women with siliconegel breast implants, in response to variousautoantigens. The IRG considered that they wouldhave to reserve judgement about this work and itwould need to be independently confirmed. Therelationship between the lymphocytic response andreported symptoms would also need to beinvestigated before conclusions could be drawn.

7. Is there histopathological evidence for animmune response in the tissue surrounding breastimplants?

Following a careful consideration of thehistopathological material provided by ProfessorShanklin, the IRG did not agree with him that any ofthe changes seen constituted evidence of an immuneresponse. In particular, neither vasculitis(inflammation of the blood vessels, indicative ofimmunological involvement) nor any otherhistological change suggesting an immune responsecould be seen in the tissues examined.

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8. Do silicones cause inflammatory reactionsthat indirectly provoke immune responses to therecipient’s own tissues?

It is well established that fluid silicones injected intotissues may produce a local inflammation,depending upon the amount injected. It has beensuggested that one possible effect of silicone gelbreast implants would be to cause an inflammatoryreaction that can result in the development of anautoimmune reaction. Several studies haveexamined whether there is an increased frequency ofautoantibodies in women with silicone gel breastimplants. While some studies claim an increasedfrequency, none of this work is adequate to permitthis conclusion. The IRG concluded that thisquestion remains incompletely resolved.

There is no suggestion that the majority of womenwith silicone gel breast implants will go on todevelop immune responses to their own tissues. It isinevitable, however, that a small proportion ofwomen with implants will do so through chancealone. At this stage, the IRG cannot rule out thepossibility that a sub-group of the women whodevelop an autoimmune response do so as aconsequence of their implant rather than due toother factors. The likelihood of this being the case isremote and the prevalence of any disease due tosilicones can be determined from an analysis ofepidemiological data (see Section 6.2) which allowsan estimate to be made of the relative risk of womenwith implants developing connective tissue disease,in comparison with the women without implants.Further studies would be needed to substantiate orrefute this possibility, and to identify any sub-groupof women at risk and the nature of any particularautoimmune response.

9. Are autoimmune syndromes found in womenwith silicone gel breast implants associated withparticular HLA variants?

T-lymphocytes, including those that take part inautoimmune reactions, recognise fragments of theirspecific target molecule that become bound to a cellmembrane carrier protein, called HLA, which showsextensive genetic variation. It is known that thelikelihood of developing autoimmune diseasesdepends, in part, upon which particular HLAvariant an individual possesses. Therefore, findingthat an unknown syndrome tends to occur morefrequently in individuals with a particular HLAvariant is important evidence that autoimmunemechanisms are involved in causing tissue damage.

Conversely, the absence of reproducible, statisticallysignificant associations between the unknownsyndrome and a specific HLA variant is evidenceagainst an autoimmune pathology.

One detailed study on HLA variants in women withbreast implants has been published (Young et al.,1995). The study claims that in women withsymptoms of pain and fatigue there is a higherfrequency of particular HLA variants. However,there are technical criticisms of this paper, which arediscussed in the Website. No independent studyconfirming this claim has been published. The IRGjudges that there is inadequate evidence to supportthe claim.

See Website on Immune Responses to Siliconefor details of the evidence considered and theIRG’s comments. www.silicone-review.gov.uk/immune

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6.2 Long-term systemic effects

The IRG considered two groups of questions inrelation to the impact of silicone gel breast implantson long-term systemic illness. The first related to anincreased risk of previously well recogniseddisorders, particularly of connective tissue diseases.Although a number of connective tissue disordershave been proposed asbeing linked, muchattention has focused onscleroderma. Suchdisorders are accepted as being rare in bothimplanted and non-implanted subjects.

The second relates to thedevelopment ofdisorders which may bea specific consequence of silicone gel breastimplants. Reports frompatient series suggestthat such complaintsconsist of combinationsof symptoms such asfatigue and muscleweakness. Thesesymptoms are oftenencountered in a varietyof less easily defineddisorders such as chronicfatigue syndrome andfibromyalgia.

The IRG considered that purely descriptive studies,either of the rare but specific connective tissuedisorders or the more frequently occurringsymptoms of general ill health, are of limited valuein the absence of similar data from a comparisongroup of women without breast implants. Theresults of such series cannot be used to demonstratethat the disorder resulted from an implant. Suchstudies, however, are useful to generate the issuesand questions that can be explored in a morerigorous way. The appropriate means ofinvestigating this is through epidemiologicalstudies, which look at groups of women who havehad silicone gel breast implants to see if they have agreater risk than the general population ofdeveloping such conditions.

Scleroderma is ageneralised disorder whichcauses hardening of theskin as well as some of theinternal organs. It has beensuggested thatscleroderma may beincreased in women whohave had silicone gel breastimplants.

Fibromyalgia is a disordercharacterised by diffusemuscle aching and fatigue,often associated withdepression as well as otherphysical symptoms. Thereis no specific diagnostictest or tests for thisdisorder which occurs at afrequency of 1-2% in thegeneral population.

6.2.1 The role of epidemiological studies toassess risk

Before considering the published evidence relatingto connective tissue disease, it is useful to have anoverall understanding of how a rigorousepidemiological study is constructed. As has alreadybeen indicated, the IRG was concerned about thequality of some of the evidence presented to themand it is important to recognise the characteristics ofa reliable study.

There are two main types of epidemiological studythat can be used to evaluate the presence andstrength of any increased risk: the cohort study andthe case control study.

Cohort studyIn a cohort study, a group of people with a specificexposure, are followed up over a period of time todetermine the occurrence of any events duringthat period, the incidence and nature of anychanges can then be compared with a randomlyidentified group of people.

In this way a group of women with silicone gelbreast implants can be followed over a period oftime and then compared with a randomly selectedgroup of women who did not have an implant.

Using this approach, the occurrence of a numberof symptoms and disease features can beinvestigated. In the majority of reported cohortstudies related to silicone gel breast implants, theoutcome is based on diagnosis reported by adoctor. The alternative is a systematic examinationof all women studied with the aim of identifyingdisease features which might otherwise not bebrought to the attention of the doctor. This latterexercise is unlikely to be a feasible proposition inwomen with silicone gel breast implants, given thesize of study and duration of follow-up thatwould be necessary to identify a sufficient numberof cases.

Case control studyIn a case control study a group of people, thecases, with a particular symptom or combinationof symptoms, is compared with an unaffectedgroup, the controls, who are free of that disorder.Typically controls are selected to be of similar ageand sex as the cases.

Thus in studying the influence of silicone gelbreast implants on disease risk, it is necessary tocompare the frequency of prior implantationbetween new cases with the disorder underinvestigation and controls over an equivalent timeperiod.

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6.2.2 Association or causation

The nature of epidemiological studies is to describethe strengths of the relationship between, in thisinstance, having an implant and development ofsystemic disease. If an increased risk was to bedemonstrated from epidemiological studies, thisdoes not necessarily imply causation. Alternativeexplanations for such a link are (i) chance findingsdue to studying small numbers and (ii) the influenceof other factors common to both implants and thedisease under investigation that might give the falseimpression of a direct link. As an example, there aredata that suggest women with breast cancer have anincreased risk of scleroderma. Therefore, womenwho had a mastectomy following breast cancer andsubsequently had an implant may be at an increasedrisk of scleroderma, which is unrelated to theirimplant. It is possible that the development of non-specific symptoms following breast implantationmay be related to the reasons for having the implantrather than being a direct consequence of the implantitself.

6.2.3 Relative and absolute risk

Most epidemiological studies considered presenttheir results in terms of relative risk, that is thenumber of times a women with an implant is atincreased (or decreased) risk compared with thebackground population risk. It may be moreimportant in public health terms to consider the

absolute increased risk. Thus a 50% increase in theoccurrence of a rare disease, which affects only oneper hundred thousand women in the generalpopulation per year, would be of substantially lessconcern than a 10% increase in the occurrence of adisorder which occurred substantially morefrequently.

See Website for further information aboutstatistical aspects and sample sizes.www.silicone-review.gov.uk/epi-stats

6.2.4 Specific connective tissue diseases

The IRG examined case control and cohort studiesconducted between 1970 and 1998, together withreviews, overviews and meta-analyses investigatingthe incidence of established connective tissuediseases.

Having considered the evidence, the IRG arrived atsix main conclusions.

1. From the case control studies, the proportion of allwomen with established connective tissue diseasewho have had a silicone gel breast implant is smalland probably no greater than the proportion ofwomen without such a disease who have had animplant.

2. From the cohort studies, the risk of developmentof established connective tissue disease in womenwho have had a silicone gel breast implant is verylow and no higher than from a similar group ofwomen who have not had an implant.

3. Given the rarity of these specific connective tissuediseases under study, and the relatively lowfrequency of women who have had a silicone gelbreast implant, it is not possible even on the studiespublished to date to exclude with certainty thatthere may be a small increase of relative risk,possibly as high as 1.5 times that of someonewithout an implant. These same data, however, arecompatible also with the equivalent degree ofprotection against the development of suchdisorders.

4. The studies reviewed only refer to specificdiagnostic groups. There may be other diseaseslinked to the development of silicone gel breastimplants for which information has not yet beengathered or not gathered in a sufficiently robustmanner.

5. Unless a specific disease entity can be identifiedthat is worthy of further investigation, it does not

The statistical analysis of both cohort and casecontrol studies is complex. Interpretation of theresults has to be undertaken with care, particularlyas the number of women investigated in thepublished studies mightnot be sufficient toprovide a definitiveanswer.

Given concerns that noindividual study,particularly in relationto rare connective tissuedisorders, is likely to bestrong enough on itsown to answer thequestion of risk,epidemiologists havealso published analysesattempting to combinethe results from theindividual studies usingthe technique of meta-analysis.

Meta-analysis A meta-analysis is atechnique used in asystematic review wherespecial statistical methodsare used to combine theresults of several studies toarrive at an overallstatistical conclusion. Thereare problems with thisapproach as it may not beappropriate to combinedata from studies where theselection factors andmethods of investigationare substantially different.

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seem appropriate to undertake furtherepidemiological investigations into the definedconnective tissue diseases at the present time.

6. In advising women whether they should orshould not undergo breast implantation, it would beuseful to compare the absolute and excess risks ofdevelopment of a connective tissue diseasefollowing an implant with risks of other adverseoutcomes following other medical interventions orprocedures. As examples, the risks observed aresubstantially lower than the risk of thrombosisfollowing the use of the oral contraceptive pill or therisk of major gastric bleed following the use ofaspirin or aspirin-like drugs.

In short, if there is a risk of connective tissuedisease, it is too small to be quantified.

See Website for details of the studies consideredand the IRG’s commentary.www.silicone-review.gov.uk/epidemiol

6.2.5 Non-specific systemic illness

There have been a wide range of non-specificsymptoms attributed to silicone gel breast implants.The most commonly reported symptoms are fatigue,headaches, dry eyes and dry mouth, musculo-skeletal aches and pains and memory loss. Someinvestigators have suggested that this collection ofsymptoms should be recognised as a new syndrome.This suggested syndrome has been given a varietyof names, including ‘human adjuvant disease’ and‘silicone poisoning’.

The IRG recognises that a significant number ofwomen who have had breast implants complain ofthis cluster of symptoms and this is being proposedas evidence that such a new syndrome exists.

However, these symptoms are common to a largenumber of conditions which are prevalent in thecommunity such as depression, fibromyalgia,chronic infection, anaemia and chronic fatiguesyndrome. There have been very few studiescomparing an unselected group of women withimplants with a matched population group toexamine the frequency of such symptoms. This isparticularly important as some of the symptoms,such as chronic widespread pain, occur in 10% ofthe normal population. (Croft et al., 1994). Thosestudies that have been carried out do not suggest,for example, any important increase in pain andfatigue over background population risk.

It is, therefore, difficult on the available data toidentify a specific syndrome associated with siliconegel breast implants when the symptoms are so

diverse and could be related to other conditions,occurring in women with an implant but unrelatedto it. The IRG noted, however, that chronic infectionaround silicone gel breast implants has been reported.It is possible that such chronic infection couldaccount for the fatigue and musculoskeletal painsnoted by some women and further research wouldbe required to determine the presence and frequencyof such infection associated with implants and itsrelationship to the level of symptoms reported.

6.3 Neurological disorders

A number of researchers have suggested thatsilicone gel breast implants may be the cause of avariety of neurological effects or of a multiplesclerosis-like syndrome. The available literature andunpublished data were reviewed by the PracticeCommittee of the American Academy of Neurologyin 1997. The Committee concluded that the existingstudies came from the weakest of their threepossible categories of evidence and did not supportany association or causal relationship betweensilicone gel breast implants and neurologicaldisorders. They recognised that well conductedobservational studies were needed to examine thisissue.

Two observational studies were published in April1998. Both were epidemiological studies, one fromDenmark (Winther et al., 1998) using their nationalregister and the other from Sweden (Nyren et al.,1998) based on their national discharge register. Thecontrols were women undergoing breast reductionsurgery. There was no statistically significantdifference in the occurrence of neurologicaldisorders between the study group and the controlgroup. However both groups had more cases thanwere expected although this was not statisticallydifferent from the historical data on the generalpopulation.

6.4 Hormonal disorders

The possibility that some low molecular weightsilicones may possess oestrogenic activity and act inan analogous manner to environmental oestrogenshas been raised. At present there are no data tosupport these putative actions. There is as yet noconsensus on which chemicals act as environmentaloestrogens and major research efforts are underwayto validate a methodology to identify suchcompounds and assess their effects.

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6.5 Effects on children of women with breast implants

There is understandable concern among women,and resultant media interest, in the possible effectsof silicone gel breast implants on the health of theirchildren.

A number of women with silicone gel breastimplants have reported that their children havedeveloped swallowing difficulties, irritability, non-specific skin rashes, fatigue and a range of othersymptoms similar to those that occur in somewomen with silicone gel breast implants.

The IRG considered the papers published on theseissues. The majority of the papers report individualcase studies and there are no epidemiological cohortor case control studies comparing the symptoms ofchildren born to women who have an implant withchildren of women who do not have an implant.

The IRG examined papers relating to swallowingdifficulties, to autoantibodies in children of womenwith an implant, and to T-lymphocyte responses tosilica. They also examined relevant studies inanimals and looked at whether there was anyevidence of silicone being present in breast milk.

The IRG concluded that the published literaturedoes not substantiate the claims that there aresignificant, clinically apparent, effects in children ofwomen who have had an implant. Whileimmunological abnormalities have been reported insome of these children, the methodologicalproblems associated with the published studiesmean that this cannot be interpreted as a clear effectof the presence of the implant. There is no evidencethat the incidence of immunological abnormalities isany greater than in the general childhoodpopulation. Because of the presence of silicone inmany forms, the exposure of children born towomen with an implant is no greater than that towhich they are exposed from other sources ofsilicone in the diet and in the environment.

See Website for a detailed discussion of theeffects on children of women with breastimplants.www.silicone-review.gov.uk/children

6.6 Silicone toxicity

Understanding the risks to human health ofchemicals requires knowledge of their toxicity. TheIRG considered evidence reviewed in previouspublications, detailed reports from manufacturersand publications in the medical and scientificliterature.

The information supplied about the local andsystemic toxicity, genetic toxicity, reproductivetoxicity and carcinogenicity showed that siliconeswere relatively bland substances. There was littlelocal reaction, except to older smooth-surfacedimplants, which tended to excite local scarring andcontraction over a period in animal studies. Therehas been no evidence of sensitisation of animals toimplants or extracts of them, pathological changesin the tissues of the immune system in animals havenot been seen after implantation of implantmaterials, nor were alterations found in specific testsof immune function in animals exposed to certainsilicones.

Tests looking with reliable, validated analyticaltechniques for the dissemination of silicones fromimplants in the body have shown either nodissemination, or the presence of only very smallamounts at distant sites following rupture of gel-filled implants, or after deliberate injection of the gel.

The substantiated risks of implants, as shown inexperiments in animals and in other laboratorystudies, and as borne out by the much more limitedinvestigation of samples from women withimplants, are local inflammatory and scarringreactions, and local infection, as around any foreignbody in the tissues. If a silicone fluid is releasedfrom a ruptured gel implant, the inflammatory andfibrotic reaction will affect a wider area. There doesnot appear to be any evidence of a conventional orvalidated type of systemic reaction, or of abnorm-alities of the immune system, in women who havereceived implants, but these aspects are furtherdiscussed in this report and previous publications(Tinkler et al., 1993; Gott and Tinkler, 1994).

The overall pattern of the findings in the toxicitytests, both the general studies of systemic actionsand the experiments examining local actions,has been consistent with conventional forms oftoxic responses. There has been no clinical,laboratory or pathological indication of unusual or unique types of reaction.

The IRG concluded that the relevant studies haveshown only local reactions to silicones. Systemicdamage and dispersal of silicone polymers

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throughout the body has not been well demon-strated, despite various claims, even after rupture of gel-filled implants. The overall pattern of thefindings is consistent with conventional forms oftoxic response, rather than any unusual reaction.

See Website for detailed discussion of toxicity of silicones.www.silicone-review.gov.uk/toxicity

6.7 Cancer

Analyses of large groups of women both with andwithout breast implants have shown that there is a slightly reduced incidence of breast cancer inwomen with breast implants. Studies looking at theincidence of other cancers have failed todemonstrate a statistically significant increaseamong women with breast implants.

Women with breast implants should continue to bescreened. Breast screening arrangements are notaffected by the presence of an implant. However,women should inform those carrying out thescreening of the presence of an implant so thatscreening techniques can be modified appropriately.

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Having reviewed all the available evidence, theIRG have reached a number of conclusions.

1. There is no histopathological or conclusiveimmunological evidence for an abnormalimmune response to silicone from breastimplants in tissue.

2. There is no epidemiological evidence for anylink between silicone gel breast implants andany established connective tissue disease. Ifthere is a risk of connective tissue disease, it istoo small to be quantified. The IRG cannotjustify recommending further epidemiologicalstudies to investigate this hypothesis.

3. Good evidence for the existence of atypicalconnective tissue disease or undefinedconditions such as ‘silicone poisoning’ islacking. It is possible that other conditions suchas low grade chronic infection may account forsome of the non-specific illnesses noted in somewomen with silicone gel breast implants.

4. The overall biological response to silicone isconsistent with conventional forms of responseto foreign materials, rather than an unusualtoxic reaction.

5. There is no evidence that children of womenwith breast implants are at increased risk ofconnective tissue disease.

6. The IRG recognised that there were issuessuch as the precise incidence of rupture wherethe scientific data were incomplete so thatrigorous conclusions could not be drawn.

7 OverallConclusions

from theScientificEvidence

Silicone gel breast implants: Report of the IRG, 199826

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8Responding to Concerns:Conclusions and Recommendations

The IRG recognises the physical and psychologicalbenefits of breast implantation but at the same timeis aware that many women are concerned about theeffects of the procedure. The IRG also recognisesthat there is some risk associated with the use of anyimplant. On the basis of information available, theIRG concludes that risks to patients associated withthe use of silicone gel breast implants are no greaterthan for other implants. It is, however, important toensure that women are able to make informeddecisions by providing clear and comprehensiveinformation about potential advantages anddisadvantages of particular products andtreatments.

Two major areas of concern were brought to theattention of the IRG by women giving oral andwritten evidence. These were:

■ poor quality of information available to assistwomen in making informed decisions aboutbreast implant surgery

■ inadequate follow-up which makes it impossibleto establish the true incidence of any short- andlong-term complications.

The IRG makes recommendations to address theseareas of concern.

8.1 Provision of adequate information before consultation

The IRG was concerned that some organisationspromote breast augmentation as a simple procedureand do not provide adequate information towomen.

Women have difficulty in obtaining reliableinformation about breast implant surgery.Information may be gathered from friends who havehad similar surgery or from advertisements in themedia. However, these sources give no informationabout the quality of the products, the service, or thefollow-up care. Women who are contemplatingbreast implantation should see their GP and obtainthe names of surgeons who are on the GeneralMedical Council (GMC) Specialist Register.

Recommendation 1

The IRG recommends that all patients undergoingcosmetic breast augmentation surgery should be ableto obtain, free of charge, from a designated body,comprehensive information about the benefits and risksof such surgery. This should be accompanied by achecklist of topics (see Figure 2) which should becovered when the possibility of an operation isdiscussed.

Recommendation 2

The IRG recommends that advertisements in all mediapromoting breast implant surgery should include astatement indicating that anyone contemplating thistype of surgery can obtain information about theoperation and its risks from a designated body.

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8.2 Provision of adequate information at the consultation

The IRG’s work has shown that women arefrequently given inadequate information about theoperation and any possible problems associatedwith it. They may be pressurised into going aheadwith the operation before they have considered fullythe advantages and disadvantages. They may not begiven full information about the possible short- andlong-term medical and financial implications of theoperation. The IRG believes that women should begiven comprehensive information about the surgeryand about any short- and long-term risks connectedwith silicone gel breast implants.

8.3 Post-operative care

The IRG considered the need for women to be givencomprehensive information about post-operativecare and possible associated problems. The IRGagreed that:

■ women should receive instructions aboutimmediate and continuing aftercare includingadvice on physical activity, pain management,time off work and what circumstances mightindicate the need to seek medical advice

■ women should be informed of the type,manufacturer and batch number of theirimplants and told to keep this information. Theyshould be given an explanation of why this maybe important

■ women should be informed that a letter will besent to their GP giving details of the operation.The purpose of the letter should be explained;should women develop problems associated withsurgery in the short- or long-term, the GP willneed to be aware of previous surgery since it maybe related to the prevailing condition

■ every GP surgery should have a copy of thereport Silicone Gel Breast Implants, The Report of theIndependent Review Group and should be aware ofthe existence of the information pack referred toat Recommendation 1.

8.4 Follow-up

The IRG considered the need for systematic follow-up for women who have silicone gel breast implants.

Women and surgeons had expressed their concernsabout the lack of long-term follow up. It was alsosuggested that the lack of effective follow-upexplained the low rate of complications seen byplastic surgeons. Because reports about problems arespasmodic, it is impossible to identify the trueincidence of complications.

The IRG agreed that:

■ women should be followed-up for a minimum ofone year with the option of longer follow-up atthe woman’s request

■ women should be given advice about how torecognise signs of rupture and told to return for afollow-up appointment if they suspect this mayhave occurred

■ women should be told that if capsular contractureoccurs, they should make an appointment withthe surgeon as soon as possible.

Recommendation 3

The IRG recommends that all women undergoing orproposing to undergo cosmetic breast augmentationsurgery should be offered the following:

1. an initial appointment with the surgeon carrying outthe operation

2. an opportunity to discuss the checklist of issues withthat surgeon. Figure 2 contains a list of issues thatshould be included in any checklist

3. information on the likely financial implications ofbreast implant surgery including the fact that furthertreatment and expenditure may be necessary at sometime in the future. These costs may include not onlyinitial consultations and operation but also regular follow-up, screening for rupture if this is thought to haveoccurred, explantation and reimplantation

4. a ‘cooling off’ period of several days between theinitial consultation with the surgeon and the operation

5. a guarantee that any deposit or payment for theoperation will be fully refunded if for any reason thewoman changes her mind, even at the very last moment,and cancels the operation

6. an assurance that they will not come into directcontact with a representative of a particularmanufacturer prior to agreeing to surgery.

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■■ The experience of the surgeon in performing thisoperation (together with information on whether onthe GMC Specialist Register, and whether amember of the British Association of PlasticSurgeons/British Association of Aesthetic PlasticSurgeons)

■■ The types of implants generally available, theadvantages and disadvantages of each and thereason for the individual decision

■■ Cosmetic effects of the operation including: ● position of pocket● position of implants● appearance of scar

■■ Information on the possible immediate post-operative effects including:

● bruising● pain● swelling● bleeding● infection● nipple sensitivity● likely recovery time

■■ Information on longer term, local effects including:● wrinkles, folds● capsule formation● gel bleed● rupture linked to the expected lifetime of theimplant, the incidence of rupture, screening forrupture, what it means if rupture occurs,symptoms that may be noted if rupture occurs,and what actions need to be taken under thesecircumstances

■■ Follow-up, including:● minimum follow-up of one year● further follow-up at woman’s request or on development of certain symptoms

■■ Possible association between silicone andgeneralised illness such as connective tissuedisease or autoimmune effects or a newconnective tissue disease-like syndrome. There isno evidence for a significant association over andabove the normal risk

■■ Breast cancer. There is no evidence for anassociation with either breast cancer or any othermalignancy

■■ Effect on breast cancer detection and screening.Women with breast implants should continue tobe screened. Breast screening arrangements arenot affected by the presence of an implant.However, women should inform those carryingout the screening of the presence of an implantso that screening techniques can be modifiedappropriately

■■ Effect on the children of women with breastimplants. There is no evidence for an increase ofillness in children of women with silicone gelbreast implants

■■ Effect on breast feeding. There is no interferencewith the ability to breast feed

■■ Information on financial implications: ● the initial consultation● operation● follow-up● possible screening for rupture, possible explantation and re-implantation

■■ Letter to the GP. Letter will be sent to GP givingdetails of the operation. Explanation of thisaction

■■ The National Breast Implant Registry● details of implant and procedure● option to participate in future follow-up

Figure 2

Suggested checklist of issues to be discussed with women considering breast implantation

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8.5 Consent for the operation

The IRG’s concerns about adequate information forwomen focused on the important issue of consent totreatment.

In 1993, the Department of Health defined consentin the following way:

“Consent is the voluntary and continuing permissionof the patient to receive a particular treatment basedon an adequate knowledge of the purpose, nature andlikely risks of the treatment including the likelihood ofits success and any alternatives to it. Permissiongiven under any unfair or undue pressure is notconsent”.

Consent to medical treatment may be oral orwritten, express or implied. For the purposes ofsurgery it is usual to obtain written consent from thepatient except in an emergency.

One matter of concern is that it appears from theevidence presented to the IRG that there is nouniformity in the approach taken to counselling ofwomen, and that in some instances women aregiven far too little information about what to expectas normal both in the immediate post-operationperiod and in the long-term.

One of two civil actions might be available incircumstances when consent is deficient. These arethe actions for trespass to the person (assault andbattery) and the action for negligence.

Trespass to the person

Assault and battery are forms of the civil action oftrespass to the person. They are also crimes, thoughit would be very unusual for criminal proceedingsto be brought against a doctor who treated a patientwithout consent.

Assault (putting a person in fear of immediatebattery), usually accompanies battery as a matter ofcourse.

In medical cases, battery may be committed if theindividual:

■ is treated against his or her will

■ consents to one treatment but receives another oran additional treatment

■ is given treatment without being told that thiswill happen

■ is treated under duress

■ agrees to treatment after being provideddeliberately with information that is wrong.

A hypothetical example might be the case of awoman who has consented to a mastectomy, and atthe same time reconstruction with a silicone gelimplant is performed without her consent to thatprocedure having been obtained before surgery.

Negligence

If the individual consents to a particular treatmentbut this was without having received appropriateinformation beforehand, this is described in legalterms as ‘negligence’.

In the United Kingdom, the general rule is that apatient is entitled to receive information concerningthe material risks associated with the treatment. Thenature and extent of that information is currentlydetermined by the Bolam test. This means that a

doctor would not befound to be negligenteven if a womanclaimed that she wasgiven insufficientinformation aboutcertain risks, if thedoctor had acted, ingood faith, on the basisof responsible, currently

held medical opinion. In breast surgery, as in manyother areas of care, medical opinion can be divided.

Despite this, the IRG is strongly of the opinion thatdoctors should give women comprehensiveinformation about the risks and benefits of siliconegel breast implants.

See Website for a detailed discussion onConsent.www.silicone-review.gov.uk/consent

Recommendation 4

The IRG recommends that a specific consent form bedeveloped which incorporates, as an integral part, thechecklist of issues (see Figure 2). The consent formshould confirm that the different types of implantavailable have been discussed with the surgeon and thetype agreed, and that all subjects on the checklist havebeen discussed to the woman’s satisfaction along withany other concerns that the woman wishes to address.This consent form should be signed by the surgeon andthe woman. One copy should be kept by the surgeon inthe notes, and one copy kept by the woman.

According to the Bolamtest, as long as the doctoris found to have acted inaccordance with aresponsible body ofmedical opinion, there canbe no finding of negligence.

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8.6 Regulation of private clinics

The IRG was concerned about varying standards ofquality assurance among the variety oforganisations offering breast implant surgery.

Recommendation 5

The IRG recommends that measures should beintroduced to ensure that proper standards of care areimplemented in clinics carrying out breast implantationwithin the private sector. In particular, a qualityassurance system, including the sending of a routineletter to the woman’s GP and clinical audit proceduresshould be standard practice within such clinics.

8.7 National Breast Implant Registry

There has been a National Breast Implant Registrysince 1993. Currently the Registry is voluntary andwomen can decide whether to have their detailsincluded.

The purposes of the Registry are to identifyinformation about short-term complications such asrupture, and to provide a source of data for futureresearch studies on the long-term effects of breastimplants. It is only by having access to acomprehensive systematically collected databasethat concerns about the possible effects of breastimplants can be investigated. The IRG emphasisedthe value of a Registry for this purpose.

If the Registry is to be used for future researchwhich will benefit all women with breast implants,it is essential to have information included on theRegistry about all implant procedures carried out inboth the NHS and the independent sector.

The IRG gave careful consideration to the issues ofconfidentiality and to the use of information on theRegistry for research purposes. It was agreed thatthe principles of confidentiality should continue tobe maintained in relation to this information.

See Website for detailed information on theNational Breast Implant Registry.www.silicone-review.gov.uk/registry

Recommendation 6

The IRG recommends that prospective registration ofdetails of each breast implant and explant operation onthe National Breast Implant Registry should becompulsory.

In addition all women should be given the opportunityto participate in long term follow-up projects with thefull understanding that they may be contacted in thefuture to provide information to facilitate research.

It should be explained to the woman that the Registrywill be used to gather accurate data on the outcomesassociated with silicone gel breast implants, includingthe incidence of rupture.

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8.8 Adverse incidents

It is essential to have information about the clinicalperformance of implants during use to be able toassess and monitor their safety and suitability in thelong-term. Information about adverse incidents canprovide an early indication of a problem with aproduct and the IRG recognised the value of theMedical Devices Agency (MDA) adverse incidentreporting system. Under this system a report ismade to the MDA about any suspected problemswith poorly designed or malfunctioning medicalproducts. Similar systems exist elsewhere such asthe FDA’s Medical Device Reporting scheme in theUSA and the Vigilance reporting system set upunder the European Directives.

The IRG emphasises the importance of using theadverse incident reporting system to ensure that anyproblems are recognised as quickly as possible.

See Website for further information aboutadverse incidents.www.silicone-review.gov.uk/incident

Recommendation 7

The IRG recommends that all clinicians should reportbreast implant related adverse incidents to the MedicalDevices Agency Adverse Incident Centre. The MDAshould provide guidance to clinicians on whichincidents should be reported.

8.9 Future research

The IRG is concerned that future research shouldenable women with silicone gel breast implants,clinicians, manufacturers and scientists to worktogether to ensure the highest levels of confidence inthe use of silicone gel breast implants. The IRGtherefore make the following recommendationsabout future areas of research.

Recommendation 8

The IRG recommends that a small steering group beset up to prioritise, plan and monitor the followingprogramme of research. Priorities should include:

■ research into the true incidence of rupture

■ research into the aetiology of symptoms exhibitedby a number of women who have had implants, inparticular to elucidate the role, if any, of sub-clinicalinfection.

The IRG recommends that the steering group shouldalso consider the need to validate the results of otherstudies, such as those by Ellis et al.

The IRG concluded that the publications of Tenenbaumet al., and Smalley et al., were not conclusive and areopen to legitimate scientific criticisms. However, inview of concerns expressed by women’s groups, theIRG recommends that there would be scientific merit indetermining whether the results of these studies canbe reproduced by independent laboratories.

Recommendation 9

Although there is currently no justification for routineregular breast investigation to detect rupture, the IRGrecommends that this subject should be kept underreview and the decision revisited in the light of possiblenew information and technical advances relating toimaging techniques used in the detection of rupture.

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Annex 1

Members of the Independent Review Group

Professor R D Sturrock, The McLeod/ArthritisResearch Campaign Professor of Rheumatology,University of Glasgow (Chairman)

Professor J R Batchelor, Emeritus Professor ofImmunology, Imperial College of Science,Technology and Medicine on the Campus ofHammersmith Hospital

Mrs V Harpwood, Senior Lecturer, Cardiff LawSchool, University of Cardiff

Professor D R London, Emeritus Professor ofMedicine, University of Birmingham; Registrar ofthe Royal College of Physicians

Mr T M Milward, Consultant Plastic Surgeon,Leicester Royal Infirmary

Professor A J Silman, Arthritis Research Campaign Professor of Rheumatic Disease Epidemiology,University of Manchester Medical School

Professor J P Sloane, Professor of Pathology,University of Liverpool

Secretariat provided by the Medical DevicesAgency

Mr G A Crosbie

Dr D M Gott

Dr S M Ludgate

Mr J J B Tinkler

Declaration of Interests

At their first meeting, members of the IndependentReview Group were asked to declare any existingrelevant interests. Mr Milward stated that he hadresumed the use of silicone gel breast implants inline with the conclusions of the previousIndependent Expert Advisory Group. ProfessorSilman stated that he had summarised the findingsof previous epidemiological studies in scientificpublications on the epidemiology of connectivetissue disease.

Advisors to the Independent Review Group

Dr A J Darby, Consultant Histopathologist, RobertJames and Agnes Hunt Orthopaedic Hospital,Oswestry

Professor A D Dayan, Professor of Toxicology, St Bartholomew’s Hospital, London

Mr J Denton, Research Scientist, Department ofPathological Science, University of Manchester

Dr M Field, Senior Lecturer, Department ofRheumatology, University of Glasgow

Professor A J Freemont, Professor of PathologicalScience, University of Manchester

Dr C Gemmell, Reader in Medical Microbiology,University of Glasgow

Professor R I Lechler, Professor of Immunology,Imperial College of Science, Technology andMedicine on the Campus of Hammersmith Hospital

Professor F D Lee, Professor of Pathology, GlasgowRoyal Infirmary

Dr D E Woolley, Reader in Cell Biology, Universityof Manchester

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Annex 2

Oral Evidence considered by the Independent Review Group

Mr P Balen Freeth Cartwright Hunt Dickens (Solicitors)

Ms N Bazire National Breast Implant Registry

Ms M Cameron Silicone Support UK (Women’s Group)

Mrs A Clwyd Member of Parliament

Ms E Coomber Survivors of Silicone (Women’s Group)

Professor R Garry Tulane University, USA

Ms S Green

Ms M Heasman Breast Implant Information Service (Women’s Group)

Mr R Levy Leigh Day and Co. (Solicitors)

Dr S Myhill General Practitioner and Allergist

Mr M Notaras British Association of Cosmetic Surgeons

Dr P O’Leary International Association of Prosthesis Manufacturers: McGhan

Dr B Purkait International Association of Prosthesis Manufacturers: Mentor

Dr P Shakespeare National Breast Implant Registry

Professor D R Shanklin University of Tennessee, USA

Professor D Sharpe British Association of Plastic Surgeons andBritish Association of Aesthetic Plastic Surgeons

Professor D R Uhlmann University of Arizona, USA (Nominated by formermanufacturers)

Ms R Urion Survivors of Silicone (Women’s Group)

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Referencescited in text

Croft, P; Schollum, J. and Silman, A. (1994) Populationstudy of tender point counts and pain as evidence offibromyalgia. British Medical Journal. 309: 696 - 699.

Ellis, T. M; Hardt, N. S; Campbell, L; Piacentini, D. A; andAtkinson, M. (1997) Cellular immune reactivities inwomen with silicone breast implants: A preliminaryinvestigation Annals of allergy, asthma and immunology. 79:151 -154.

Gott, D. M; and Tinkler, J. J. B. (1994) Silicone Implantsand Connective Tissue Disease: evaluation of evidence foran association between the implantation of silicones andconnective tissue disease. Medical Devices Agency,Department of Health: London.

Nyren, O. McLaughlin, J. K; Yin, L. Josefsson, S; Engqvist,M; Hakelius, L; Blot, W. J; and Adami, H. O. (1998)Neurology. 50: 956 - 962.

Smalley, D. L; Shanklin, D. R; Hall, M. F; Stevens, M. V;and Hanissian, A. (1995) Immunologic stimulation of T-lymphocytes by silica after use of silicone mammaryimplants. FASEB Journal. 9: 424 - 427.

Smalley, D. L; Levine, J. J; Shanklin, D. R; Hall, M. F; andStevens, M. V. (1996/1997) Lymphocyte response to silicaamong offspring of silicone breast implant recipients.Immunobiolology. 196: 567 - 574.

Tenenbaum, S. A; Rice, J. C; Espinoza, L. R; Cuéllar, M. L;Plymale, D. R; Sander, D. M; Williamson, I. I; Haislip, A.M; Gluck, O. S; Tesser, J. R. P; Nogy, L; Sribrny, K. M;Bevan, J. A; and Garry, R. F. (1997) Use of antipolymerantibody assay in recipients of silicone breast implants.Lancet; 349: 449 - 454.

Tinkler, J. J. B; Campbell, H. J; Senior, J. M.; and Ludgate,S. M. (1993) Evidence of an association between theimplantation of silicones and connective tissue disease.Medical Devices Directorate Report MDD/92/42Department of Health: London.

Winther, J. F; Bach, F. W; Friis, S; Blot, W. J; Mallemkjer, L.Kjellar, K; Hagsted, C; McLaughlin, J. K; and Olsen, J. H.(1998) Neurology. 50: 951 - 955.

Young, V. L; Nemecek, J. R; Phelan. D. L. and Schorr, M.W. (1995) HLA typing in women with breast implants.Plastic & Reconstructive Surgery. 96: 1497 - 1519.

See Website for a full list of referencesconsidered by the IRG.www.silicone-review.gov.uk/reference

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Glossary

Adjuvant: a substance which enhances antibodyproduction.

Antibody: a protein that is manufactured by certainlymphocytes (types of white blood cell) which reactswith a specific antigen in the body.

Antigen: a substance that can trigger an immuneresponse resulting in the production of an antibodyas part of the body’s defense against disease.

Autoantibody: an antibody which reacts with theindividual’s own tissues because it recognises theseas foreign antigens.

Autoimmune reaction: a response arising from anddirected against the individual’s own tissues.

Axillary lymph nodes: a group of glands in thearmpit.

Brachial plexus: a group of nerves in the armpitwhich supply the arm.

Capsular contracture: shrinkage of the fibrouscapsule, noticeable as an apparent hardening of thebreast.

Capsulotomy: the creation of an opening throughthe scar tissue forming around the breast implant,by application of external pressure.

Fibrous capsule: a wall of scar tissue around thebreast implant.

Gel bleed: diffusion of small molecules of the liquidcomponent of silicone gel through the intact shell.

Haematoma: a mass of extra-vascular clotted orpartially clotted blood, confined within a tissue orspace.

Polydimethylsiloxanes (PDMS): polymers ofdimethylsiloxane, referred to throughout this reportas silicone.

Staphylococcus epidermidis: a bacterium whichexists as part of the normal skin microflora causingno ill effects unless introduced into the human body.

Subclinical: this denotes the presence of a conditionwithout obvious symptoms; may be an early stagein the evolution of a disease.

Systematic review: an exercise which aims toreview all relevant published studies in the scientificliterature on a specific topic, evaluates their qualityand the results obtained with the aim of reaching anoverall conclusion.

T-lymphocyte: a particular type of long-lived whiteblood cell.

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© Crown Copyright

Copies of this report are available from:

Silicone Gel Breast Implants Independent Review Group9th FloorHannibal HouseElephant and CastleLondon SE1 6TQ

Telephone 0171 972 8000 July 1998/30k

Silicone Gel Breast ImplantsThe Report of the Independent Review Group


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