1640 dr wong nan soon cancer screening and saving lives, healthcare costs

Cancer Screening Saving Lives and Healthcare Costs

Dr Wong Nan Soon Consultant Medical Oncologist

Oncocare Cancer Centre Mt Elizabeth Medical Centre

Adjunct Associate Professor

Department of Clinical Sciences Duke-NUS

Avoid Overzealous Screening!

Message

• Cancer is the commonest cause of death in Singapore

• Cancer incidence increases with age

BUT

• Effective cancer screening is available for common malignancies

• Cancer awareness and compliance with screening recommendations can contribute to healthy aging workforce

Scope

• Biology of cancer

• Cancer epidemiology in Singapore

• Principles behind screening

• Details of screening tests available

What Exactly is Cancer?

Hanahan and Weinberg. Cell 2011

Stepwise Progression of Cancer

Dynamics of Cancer: Incidence, Inheritance, and Evolution. Frank SA.Princeton (NJ): Princeton University Press; 2007. Vogelstein et al.,New Engl J Med 1988

Cancer: Top Killer in Singapore

Ministry of Health: Statistics

Cancer Burden

Singapore Cancer Registry Interim Report 2005-2009

Common Cancers by Gender

Singapore Cancer Registry Interim Report 2005-2009

Age Specific Cancer Incidence

Singapore Cancer Registry Interim Report 2005-2009

What is Prevention

• Primary prevention – Prevents onset of disease – Removes risk factors eg smoking cessation, avoiding

HRT

• Secondary – Detects disease at early asymptomatic stage – Stops disease progression – Eg screening for breast cancer, colon cancer

• Tertiary – Prevents disease deterioration and complications – Eg lowering glucose in known diabetic

What is Screening

• Detection of unrecognized risk factor or disease in well patients

• Can be part of primary or secondary prevention

• Involves clinical examination, blood tests, procedures such as mammography, colonoscopy

Should We Screen Everyone for Every Disease?

• Incidence of disease

• Morbidity and mortality of disease

• Is primary prevention possible

• Is early intervention effective/ curative

• Performance of screening test

– Specificity and sensitivity

– Safety, side effects, acceptability

– Cost

Evaluating Screening Test Avoiding Bias

• Screen detected cancers vs symptomatic cancers

– Lead time bias

– Length time bias

– Overdiagnosis bias

– Selection bias

Recommended Screening

Cancer Type Average Risk High Risk

Breast cancer Yes Yes

Colorectal cancer Yes Yes

Cervical cancer Yes Yes

Ovarian cancer No Yes (BRCA mutation)

Uterine cancer No Yes (Lynch syndrome)

Lung cancer No Yes (Heavy smokers)

Liver cancer No Yes (Hepatitis B carriers)

Prostate cancer No Yes (Strong family history)

NPC No Yes (Strong family history)

Mammography

Mammography

Screening Mammogram

Study Protocol Frequency Population Subgroup Invited Control F/U RR (95%CI)

HIP

(1963-1969)

2V MM,

CBE

q12m x 4 40-64 40-49

50-64

14432

16568

14701

16299

18

18

0.77(0.53-1.11)

0.80(0.59-1.08)

Edinburgh

(1979-1988)

1 or 2V

MM, CBE

q24m x4 45-64 45-49

50-64

11755

11245

10641

12359

14

10

0.83(0.54-1.27)

0.85(0.62-1.15)

Kopparberg

(1977-1985)

1V MM q24mx4 40-74 40-49

50-74

9650

28939

5009

13551

20

20

0.76(0.42-1.40)

0.52(0.39-0.70)

Ostergotland

(1977-1985)

1V MM q24mx4 40-74 40-49

50-74

10240

28229

10411

26830

20

20

1.06(0.65-1.76)

0.81(0.64-1.03)

Malmo

(1976-1990)

1 or 2V MM q18-24m x5 45-69 45-49

50-69

13528

17134

12242

17165

12.7

9

0.64(0.45-0.89)

0.86(0.64-1.16)

Stockholm

(1981-1985)

1V MM q28mx2 39-59 39-49

50-59

11724

9276

12015

14217

11.4

7

1.01(0.51-2.02)

0.65(0.4-1.08)

Gothenberg

(1982-1988)

2V MM q18mx5 39-59 39-49

50-59

11724

9276

14217

16394

12

13

0.56(0.32-0.98)

0.91(0.61-1.36)

CNBSS1

CNBSS2

(1980-1987)

2V MM

CBE

Q12m x5 40-49

50-59

40-49

50-59

25214

19711

25216

19694

11-16

13

1.07(0.75-1.52)

1.02(0.78-1.33)

UK AGE

(1991-1997)

2V MM

year 1 then

1 V MM

Q12m x 7 39-41 - 53914 107007 11 0.83 (0.66-1.04)

Smith RA, Dorsi CJ. Screening for breast cancer in : Diseases of the breast, Lippincott WW, Philadelphia USA, 2004

Benefits and Risks

Fletcher and Elmore, New Engl J Med 2003

Warner, New Engl J Med 2011

Impact at Population Level

Trends in female breast cancer mortality rates by ethnicity, USA 1975-2002

Screening Mammography Guidelines

Agency Frequency Age 40-49 Age 50-69 Age>69

US Preventive Services

Task Force

2 yrs Discuss

Q2 yrs

Yes Yes

Canadian Task Force on

Preventive Health Care

1-2 yrs Discuss Yes No

ACS 1 yr Yes Yes Yes

NCI 1-2 yrs Yes Yes Yes

HPB Singapore/MOH 2 years Discuss

Q1 year

Yes -

Other Modalities

– MRI • Prospective data in familial breast cancer1,2

• Higher sensitivity, lower specificity

• Impact on mortality not determined

• Higher cost

– Digital mammography • Recent randomised trial showed higher accuracy in women

age <503

1. Warner E et al. JAMA 292:1317, 2004

2. Kriege M et al. NEJM 351:427, 2004

3. Pisano ED et al. NEJM 353:1846, 2005

Colon Cancer Screening

What is Colorectal Cancer

Symptoms and Signs of Colorectal Cancer

• Blood in stools

• Change in stool calibre

• Change in bowel habits

• Sense of incomplete bowel emptying

• Abdominal distention

• Weight loss

• Anemia

Why is Screening Useful?

• There is a long period in the early stages where there are no symptoms.

• Colorectal cancer develops from polyps or adenomas. Removing polyps prevents cancer.

How is Screening Performed?

• Faecal Tests – Occult blood test

• Guaic based • Immunohistochemical test

– Stool DNA

• Colonoscopy • Virtual (CT) colonoscopy • Flexible sigmoidoscopy • Double contrast barium enema

Faecal Occult Blood Tests

• Detection of microscopic amounts of blood in the stool

• Cancers may bleed an invisible amount during the early stages

• Different types of test kits are available – Guaic based

– Immunohistochemistry

Faecal Occult Blood Test

Faecal Occult Blood Test

Faecal Occult Blood Test

• If positive, colonoscopy required

• If negative, may be sampling error

Faecal Occult Blood Test

• False positive – Diverticular disease

– Haemorrhoids

– Guaic based: red meat, raw turnips, broccoli, cauliflower, radish

• False negative (guaic based tests) – Non bleeding polyp/ tumour

– Medications: aspirin, NSAIDS, vitamin C >750 mg per day

Benefits of FOBT

• Incidence of stage 4 reduced by 32-47%

• Incidence of colorectal cancer reduced by 20%

• Death from colorectal cancer reduced by between 15% to 30% – Absolute benefit 0.8-4.6 per 1000 patients

screened

– Numbers needed to screen 217-1250

Walsh et al. JAMA 2003

Colonoscopy

• Gold standard

• Enables screening and intervention

• No randomized trials

• Based on cohort studies – Reduces incidence of

colorectal cancer by 76%

– False negative rate 5-12%

– Complication rate 0.03-0.17%

Who, When, How Often

What is Cervical Cancer

Symptoms and Signs of Cervical Cancer

• Vaginal bleed

– Intermenstrual

– Postcoital

• Vaginal discharge

• Backpain

Screening for Cervical Cancer

Cervical Cancer

• Rationale for Screening – No randomized trials

– Convincing evidence from observational studies • Introduction of screening programs

– Decreased incidence of cervical cancer

– Decreased cervical cancer deaths

– Calculations suggest 90% reduction in cervical cancer mortality

Cervical Cancer Primary Prevention

• Bivalent

• Quadrivalent

• Best efficacy when given prior to HPV exposure

• Does not alter need for screening

Ministry of Health Guidelines on Screening

• Cervix

– Women who have had sex before or are

sexually active should go for a Pap smear

once every 3 years

– Start at age 25

Conclusion

• Effective cancer screening is available for common malignancies

• Cancer awareness and compliance with screening recommendations can contribute to healthy aging workforce

• Seek help from a medical professional to tailor a suitable screening program

• Avoid overzealous screening