CANCER SCREENING 2008: Updates and Evidence Leah Karliner, MD, MCR Assistant Professor of Medicine Division of General Internal Medicine UCSF.

CANCER SCREENING 2008: Updates and

Evidence

Leah Karliner, MD, MCR

Assistant Professor of Medicine

Division of General Internal Medicine

UCSF

OUTLINE

Evaluating Screening Tests: general principles

Colon cancer screening: which test is best?

Prostate cancer screening: to screen or not to screen?

Ovarian cancer: to screen high risk?

PRINCIPLES OF SCREENING

Disease has high prevalence

Disease has serious consequences

Detectable preclinical phase

Treatment for presymptomatic disease is more effective than after symptoms develop

Positive impact on clinical health outcomes: early detection reduces cancer mortality

EFFECTIVENESS OF TEST

Tests should be simple, inexpensive and acceptable with a high sensitivity and specificity

Number of false positives is acceptably low

EFFECTIVENESS OF TEST

Questions to be answered when evaluating/comparing tests:

Who will be tested? What tests will it supplement or replace? Is the new test safer? Is the new test less costly? Is the test more specific (excluding cases of

non-disease)? Is the new test more sensitive (detecting more

cases of disease)? Is wide-spread use of the test feasible in

practice?

SCREENING:OTHER CONSIDERATIONS

Involving patients in the decision– What are the patient’s co-morbid conditions?– Associated life expectancy, feasibility of

treatment, effects of treatment on quality of life?

– What will you do with the results?

OUTLINE

Evaluating Screening Tests: general principles

Colon cancer screening: which test is best?

Prostate cancer screening: to screen or not to screen?

Ovarian cancer: to screen high risk?

COLON CANCER

COLORECTAL CANCER: Principles of Screening

Disease has high prevalence: Second most common form of cancer in the U.S.

Disease has serious consequences: second highest cancer mortality rate overall in U.S.

Detectable preclinical phase – polyps Treatment for pre-symptomatic disease is more

effective than after symptoms develop - yes Screening reduces cancer mortality:

– Several studies have shown that screening with fecal occult blood test (FOBT) or sigmoidoscopy is associated with a reduction in colorectal cancer mortality

COLON CANCER SCREENING

RECOMMENDATIONS

U.S. Preventive Services Task Force recommends screening all persons over 50 – Benefits of screening outweigh potential harms– Quality of evidence, magnitude of benefit and

potential harms vary with each method – Unclear which is the best test: FOBT, FOBT plus

sigmoidoscopy, colonoscopy

Changing Incidence

Colon cancer incidence rates – decreased for White and Asian-Pacific Islander

men and women in U.S. from 1995-2004;– were stable for African American, Latino and

Native American men and women;

Decrease in incidence largely due to screening and removing pre-cancerous polyps

Disparities in incidence rate decline also likely due to disparities in screening rates

– Espey et al. Annual report to the nation on the status of cancer, 1975-2004, featuring cancer in American Indians and Alaska Natives. Cancer. Oct 15, 2007.

AVAILABLE TESTS

Tests should be simple, inexpensive and acceptable with a high sensitivity and specificity: ????

Commonly used tests:– Fecal occult blood test– Sigmoidoscopy– Colonoscopy

Newer tests:– CT Colonography– Fecal DNA testing

WHICH TEST?

Are the tests equally safe? Are the tests equally costly? Are the tests equally specific? Are the tests equally sensitive? Is wide-spread use of the test feasible in

practice?

TEST ISSUES Sigmoidoscopy

– Fair evidence for reducing mortality– Sigmoidoscopy alone can miss proximal neoplasia –

a positive test needs to be followed by colonoscopy

GFOBT – Good evidence for reducing mortality– Trials used 6 sample every 1-2 years– Positive test needs to be followed by colonoscopy

FIT (fecal immunochemical test)– More sensitive than GFOBT; somewhat less specific– Specific to human globin; no dietary restrictions;

less direct stool handling

FIT compared to GFOBT

Screening Populations: 3 cohort studies–FIT appear to be more sensitive in detecting CRC and large ≥ 1cm adenomas than Hemoccult II;

–FIT appear to be somewhat less specific (higher false positive rates) than Hemoccut II

FIT GFOBT

(Hemoccult II)

Sensitivity 57% - 82% 32% - 50%

Specificity 95% – 96% 98%

IS COLONOSCOPY “BETTER?”

Two observational studies of patients undergoing colonoscopy

Goals: – prevalence and location of colonic neoplasia in

asymptomatic patients, and – Assess risk of proximal advanced neoplasia in

patients with or without distal neoplasia Did NOT assess morbidity and mortality

IS COLONOSCOPY “BETTER?”

Colonoscopy showed some lesions that would have been missed by sigmoidoscopy alone– distal polyps were a predictor of proximal

neoplasia, – but some patients with proximal neoplasia did

not have distal polyps

If sigmoidoscopy alone had been done and if every adenomatous polyp triggered colonoscopy, 80% of high risk lesions would have been detected

SCREENING COLONOSCOPY?

Would proximal lesions have been detected by FOBT?

No assessment of morbidity and mortality

SCREENING COLONOSCOPY?

More sensitive than FOBT/sigmoidoscopy More specific than FOBT Higher risk (diagnostic colonoscopies have

1/2000 perforation rate; with polypectomy 1/500-1000)

More costly? (USPSTF says all of these screening methods are probably cost-effective)

Presumed to save lives because used as diagnostic test in FOBT studies, but at higher rate than FOBT?

Feasibility in practice dependent on availability of gastroenterologists and insurance coverage

CT COLONOGRAPHY

Non-invasive colon imaging method using thin section CT

Test characteristics in large 2003 study – 3-D scan– N=1,233 average risk individuals, single site– Sensitivity

» 94% for polyps ≥8 mm» 89% for polyps ≥6 mm

– Specificity» 96% for polyps ≥10 mm» 80% for polyps ≥6 mm

•Pickhardt, 2003

CT COLONOGRAPHY

Multicenter study of screening population– 615 participants at 9 hospitals

Two-dimensional scans Sensitivity

– 55% for lesions ≥10 mm– 39% for lesions ≥6 mm

Specificity– 96% for lesions ≥10 mm– 91% for lesions ≥6 mm

•Cotton, 2004

CT COLONOGRAPHY

Kim et al NEJM Oct 4, 2007 Single site; 3-D scans Comparison of diagnostic findings in two parallel large

case series of CT colonography (3,120) and optical colonoscopy (3,163)

If CTC patient had polyp ≥6mm then offered same day therapeutic colonoscopy (7.9%)

Found – similar rates of advanced neoplasia (3.2% vs 3.4%); – a few more invasive cancers found on CTC (n=14 vs 4)

5 times as many polypectomies done in colonoscopy group

CT COLONOGRAPHY

Cornett et al Am J Gastroenterology; June 2008 159 patients with positive result on screening

CTC Subsequent optical colonoscopy CTC overall miss rate 18.9% (25/132); but only

6.2% (4/65) for polyps >9mm Of the 4 large polyps missed, 2 had poor CTC

colonic distention, 3 were sessile False positive CTC referral (no polyp seen on

optical colonoscopy) = 5%

CT COLONOGRAPHY

Requires bowel prep and insufflation Patients do not necessarily prefer over

colonoscopy (50-50 in Kim et al study) Test interpretation is very time consuming Cost effectiveness

– Assuming 100% sensitivity and specificity– To replace colonoscopy, it would have to be less

than 50% the cost of colonoscopy and compliance would have to be 15-20% better

•Sonnenberg, 1999

FECAL DNA TESTING

DNA alterations in colorectal cancer can be detected in the stool

Potential advantages– Non-invasive– No preparation– Detection along entire length of the colon

FECAL DNA TESTING

Evaluated as a screening test in asymptomatic individuals aged 50 and older

Fecal DNA test (21 mutations), Hemoccult II and colonoscopy

4404/5486 completed all three aspects of the study

Subgroup of 2507 patients were analyzed• Imperiale, 2004

FECAL DNA TESTING

Fecal DNA Hemoccult II

Sensitivity for invasive cancer

51.6% 12.9%

Sensitivity for invasive cancer/adenoma with high grade dysplasia

40.8% 14.1%

Sensitivity for advanced neoplasia

18.2% 10.8%

Specificity 18.2% 10.8%

FECAL DNA TESTING

20% of the subjects either did not provide samples or did not have colonoscopy

Many were aged 65 and over Both FOBT and fecal DNA had relatively

low sensitivities compared with what was expected based on prior studies

FECAL DNA: REMAINING QUESTIONS

Are health outcomes improved?– Even if we assume benefit based on FOBT trials,

how much? Do the benefits outweigh the risks?

– Public expectations about accuracy of DNA testing Frequency of testing? Interval unclear Cost

– $400 to $800 vs $3 to $40 for FOBT

WHICH TEST?

Most preventable cases of colon cancer are found in those who have never been screened

If we screened with the currently available tests at the recommended intervals, we could make a big impact – particularly in ethnic minorities who have lower screening rates than whites

Any screening is better than no screening for reducing colorectal cancer mortality

SCREENING FOR HIGH RISK POPULATIONS

Family History 1st degree relative with colon CA or adenomatous polyp

diagnosed at age <60, or 2 1st degree relatives with colon ca at any age– Screening colonoscopy age 40 or 10 years prior to earliest family

diagnosis– Repeat screen every 5 years

1st degree relative colon CA/adenomatous polyp diagnosed at age ≥ 60, or two 2nd degree relative with colon ca at any age– Screened as average risk persons, starting age 40

Familial Adenomatous Polyposis (FAP)– Annual sigmoidoscopy starting age 10-12

HNPCC– Colonoscopy q1-2 years beginning age 20-25 or 10 years prior to

earliest CA diagnosis in family

SCREENING FOR HIGH RISK POPULATIONS

History of Adenomatous Polyps:surveillance based on pathology and number of adenomas at most recent prior colonoscopy

Any adenoma w/high grade dysplasia or villous features, or multiple adenomas (≥3)– Repeat colonoscopy in 3 years

1-2 small (<1cm) tubular adenomas w/ low grade dysplasia only– Repeat colonoscopy in 5 years-10 years

OUTLINE

Evaluating Screening Tests: general principles

Colon cancer screening: which test is best?

Prostate cancer screening: to screen or not to screen?

Ovarian cancer: to screen high risk?

Prostate Cancer

PROSTATE CANCER: SHOULD WE SCREEN?

Disease has high prevalence: Most commonly diagnosed cancer in U.S. men– 10% lifetime risk– 30% of men have prostate cancer at autopsy

Disease has serious consequences: variable; prostate cancer may be a benign disease for many men

Detectable preclinical phase – ?PSA Treatment for pre-symptomatic disease is more

effective than after symptoms develop - Does early detection do more good than harm or vice versa?Complications of prostate cancer treatment– 8.4% incontinence– 60% impotence

• Prostate Cancer Outcomes Study 24 month follow up Screening reduces cancer mortality: ???

DOES SCREENING DECREASE MORTALITY? EPIDEMIOLOGIC

EVIDENCE

Prostate cancer mortality has decreased following the introduction of prostate cancer screening

Reduction in mortality followed an initial increase in incidence – Due to PSA screening? – Changes in treatment?– Serendipitous effects of non-cancer-directed

treatments?

IS TREATMENT OF EARLY DISEASE EFFECTIVE?

Does treatment of early prostate cancer reduce morbidity and mortality?

Radical prostatectomy vs. watchful waiting– RCT of 695 men– reduction in all-cause mortality, reduction in prostate

cancer specific mortality, metastatic disease and local progression

– Absolute reduction in prostate ca specific mortality 30 in prostatectomy group vs. 50 in watchful waiting

group» 5-year follow-up 2% fewer deaths in prostatectomy group» 10 year follow-up 5.3% fewer deaths in prostatecomy group

– Bill-Axelson, NEJM 2005

RANDOMIZED CLINICAL TRIALS

46,000 men underwent DRE and PSA – 11 year follow-up– 23% of invited group and 6.5% of comparison

group underwent screening– Decrease in prostate cancer mortality, but small

numbers of deaths overall

(10/7,348 screened vs. 74/14,231 unscreened: NNS=263)

Labrie, Prostate 2004

ONGOING RCTs

PLCO trial sponsored by the NCI : – Intervention group (38,350) annual screens (PSA x

5 and DRE x 3) vs. usual care (38,355) in healthy men 55-74

– Enrolled 1992-2001; following for 13 years

European Randomized Study of Screening for Prostate Cancer (ERSPC) – 8 countries– Randomizing close to 220,000 men to screening

with PSA, DRE (and for positive tests transrectal ultrasound) vs usual care

– Results expected “between 2008-2010”

DIGITAL RECTAL EXAMINATION

One-third of prostate cancers occur in areas which can be reached

Higher sensitivity performed by urologists An abnormal digital rectal examination

increases the likelihood of prostate cancer somewhat

A negative examination does not change the likelihood of a clinically significant prostate cancer– Low sensitivity of the examination

PSA SCREENING: TEST ISSUES

15% of men over the age of 50 have an elevated PSA

PSA >10 ng/ml: – 66% have prostate cancer

PSA 4-10 ng/ml: – 22% have prostate cancer

PSA SCREENING: TEST ISSUES

Levels of 4.0 ng/ml or less have typically been considered to be normal

Results from the Prostate Cancer Prevention Trial show that prostate cancer is not rare even in these men– 27% cancer in those with PSA 3.1 to 4.0 – 24% in those with PSA 2.1 to 3.0– 17% in those with PSA 1.1 to 2.0– 10% in those with PSA 0.6 to 1.0– 7% in those with PSA up to 0.5

How many cancers would be clinically important?

– Thompson IM et al, NEJM, 2004

Risk Calculation Based on date from the Prostate Cancer Prevention

Trial Can use for men

– ≥ age 50 – without a h/o prostate cancer, – who have undergone PSA and DRE for screening within the

past year

Assesses risk for biopsy positive prostate cancer and risk for high grade disease

Takes into account: age, ethnicity, PSA and DRE results, history of negative biopsy

Thompson IM & Ankert DP; CMAJ June 19, 2007

www.compass.fhcrc.org/edrnnci/bin/calculator/main.asp

PROSTATE CANCER SCREENING:

RECOMMENDATIONS

USPSTF: insufficient evidence to recommend for or against routine screening for prostate cancer using PSA or DRE in men <75– PSA can detect early prostate cancer, but inconclusive

evidence about whether early detection improves health outcomes

– Discussion age 50-75 (or age 45 for high risk: African American; 1st degree relative with h/o prostate ca)

Recommends against screening in men >75

ACP: individualize the decision to screen after discussion with patient about potential benefits and harms

ACS: offer PSA and DRE annually starting at age 50, or age 40-45 for high risk (African American; strong family history); men asking their doctor to decide should be screened

OUTLINE

Evaluating Screening Tests: general principles

Colon cancer screening: which test is best?

Prostate cancer screening: to screen or not to screen?

Ovarian cancer: to screen high risk?

OVARIAN CANCER

OVARIAN CANCER: SHOULD WE SCREEN?

Disease has high prevalence: 8th most common cause of CA in women

Disease has serious consequences: Usually diagnosed late (>60% stage III or IV): 5th cause of CA death in women

High risk group: family historyLifetime risk of ovarian cancer– No affected relatives 1.2%– One affected relative 5%– 2 affected relatives 7%– Hereditary syndrome 40%

Treatment for pre-symptomatic disease is more effective than after symptoms develop: Ovarian cancer limited to the ovaries is associated with a much higher survival rate– Overall 50 year survival: 35%– Early stage survival: 90%

Does screening decrease mortality: ???

OVARIAN CANCER: SCREENING TECHNIQUES

Serum CA-125 assay Trans-vaginal ultrasound Serum CA-125 plus ultrasound

OVARIAN CANCER SCREENING: CLINICAL

TRIAL

22,000 U.K. women Annual screening vs no screening for 3

years with 7 year follow-up Screening

– CA-125– Ultrasound if elevated CA-125– Surgical evaluation if ultrasound abnormal

Slight increase in mean survival No difference in mortality

» Jacobs et al, Lancet 1999

OVARIAN CANCER SCREENING:

CONCLUSIONS

Many women must be screened to detect a few cases

Small increase in survival:– Is it worth it?

Low disease prevalence limits utility of the tests despite high sensitivity and specificity

SCREENING RECOMMENDATIONS

USPSTF: potential harms outweigh potential benefits

NIH Consensus Conference: Insufficient evidence Many organizations recommend annual pelvic

examination– No evidence

Although there are no data regarding screening in high risk women (family history; BRCA1 and BRCA2 carriers; HNPCC), experts recommend:– annual screening with recto-vaginal pelvic

examination, CA-125 and trans-vaginal ultrasound– BRCA1 and BRCA2 carriers can consider prophylactic

oophorectomy

FUTURE TRIALS PLCO Trial

– 74,000 women aged 55-74– CA-125 at entry and annually for 5 years– Annual transvaginal ultrasound – 13 year follow-up– Novel biomarkers are being investigated

United Kingdom Trial of Ovarian Cancer Screening– RCT 200,000 women with 7 year follow-up to

complete in 2010– CA-125– Ultrasound if elevated CA-125– Surgical evaluation if ultrasound abnormal

SUMMARY OF RECOMMENDATIONS

Ovarian cancer: – maybe in high risk women only; otherwise await

PLCO trial– women at high risk should consider oral

contraceptives (37% reduction in incidence)

SUMMARY OF RECOMMENDATIONS

Colon cancer: any screening is better than no screening, use commonly available tests

Consider CT colonography if your center has 3-D technology, experienced radiologists, willing patient population, easy access to follow-up colonoscopy

Await further research on fecal DNA

Prostate cancer: discuss pros and cons of PSA with eligible men age 50-70; await PLCO trial

Consider using risk calculation in discussion of screening and in discussion of biopsy

WHERE TO GO FOR THE EVIDENCE

U.S. Preventive Services Task Forcehttp://www.ahrq.gov/clinic/uspstfix.htm American Cancer Society Guidelines for Early

Detection of Cancerhttp://www.cancer.org/ National Cancer Institutehttp://www.cancer.gov/cancertopics/screening Technology Evaluation Center / Blue Cross - Blue

Shield Associationhttp://www.bcbs.com/tec/whatistec.html California Technology Assessment Forum / Blue

Shield of California Foundationhttp://www.ctaf.org/

ADDITIONAL SYLLABUS SLIDES

LUNG CANCER

LUNG CANCER

LUNG CANCER: Principles of Screening

Disease has high prevalence: In US in 2007, there will be an estimated 213,380 new cases of lung cancer

Disease has serious consequences: – #1 cause of cancer mortality for both men & women in US

Detectable preclinical phase – ??? Treatment for pre-symptomatic disease is more

effective than after symptoms develop – when detected in Stage I, improves 5-year survival from 15% to 40-70%

Screening reduces cancer mortality:– Neither x-rays nor sputum cytology screening reduces

mortality, what about CT scans?

LOW DOSE SPIRAL COMPUTERIZED

TOMOGRAPHY (LDCT)

Helical, volumetric studies (like conventional chest CT)

Continuous data acquisition Scans entire lung in < 20 seconds (single

breath hold) No IV contrast More radiation exposure than CXR, less than

conventional CT

Published English-language studies of LDCT screening for

lung cancer

1 cross-sectional 6 longitudinal cohort studies 1 randomized control trial –

feasibility pilot study comparing LDCT to CXR

4 studies with high risk populations (smokers/former smokers)

4 studies with mixed-risk populations (ranging from 46-86% smokers)

Published English-language studies of LDCT screening for

lung cancer Overall the studies show that LDCT:

– can detect lung cancer– tends to detect early stage (Stage I) cancers (53%-

93% of cancers found at baseline screen)

The studies with high-risk only populations– 1.2-2% prevalence of lung cancer on LDCT– 0.6-2% incidence of lung cancer on follow-up/annual

screens

One study compared mortality to historical controls and found no difference (Swenson et al)

– 2.8/1000 person-years in CT screened population versus 2.0/1000 person years in Mayo Lung Project participants

LDCT screening for lung cancer

Henschke et al Oct 2006 NEJM: results of the International- Early Lung Cancer Action Project (I-ELCAP)

– 83% smokers; 12% second hand smoke; 5% occupational exposure

– N=31,567– Extensive protocol for follow-up of abnormal scans– Formal adjudication of all cases– Longitudinal cohort study– Baseline screen by LDCT– Follow-up screen for most participants– No comparison group

LDCT screening for lung cancer

Baseline Screen (n= 31,567)– 4,186 positive test– 405 (1.3%) lung cancers

Annual Screen (n=27,456)– 1,460 positive test– 74 (0.27%) lung cancers– 5 cases interim diagnoses of lung cancer – 412/484 (85%) Stage I

Estimated 10-year lung cancer specific mortality (average follow-up 5 years) – All cancers 20%– For Stage I cancers 12%

Potential Biases

Lead-time biasScreening identifies disease earlier, but does not increase actual survival

False increase in apparent survival time by diagnosing cases earlier

From: Newman & Kohn, 2006

Potential Biases

Length-time bias False increase in apparent survival time by

diagnosing more indolent disease

From: Newman & Kohn, 2006

Potential Biases

Overdiagnosis bias (pseudo-disease bias) False increase in apparent survival time by

misclassifying detected abnormality as disease which would never have presented clinically

Volunteer bias People who participate in screening trials may

be inherently different (healthier) than those who do not

--healthier habits, --better access to health care, and --different education and income levels

LUNG CANCER SCREENING RECOMMENDATIONS

The U.S. Preventive Services Task Force (USPSTF)

evidence is insufficient to recommend for or against screening asymptomatic persons for lung cancer with either low dose computerized tomography (LDCT), chest x-ray (CXR), sputum cytology, or a combination of these tests.

LDCT screening for lung cancer: potential harm

Up to 93% of the non-calcified nodules >4mm found in the studies have been false-positives

All require follow-up: conventional CT to surgical biopsy

All follow-up carries some risk: increased radiation exposure to bleeding/infection/death

Risks of higher radiation exposure due to LDCT at regular intervals are unknown

LDCT screening for lung cancer

LDCT promising modality to screen for lung cancer and find it early

Studies to date have not been designed to account for potential biases

Do not yet have convincing data that LDCT screening for lung cancer leads to decreased mortality.

Ongoing large NCI RCT: National Lung Screening Trial– Results anticipated in 2009

Smoking Cessation!

Lung cancer incidence rates have stabilized in women and are declining in men in the U.S.

True across race-ethnicities

– Espey et al. Annual report to the nation on the status of cancer, 1975-2004, featuring cancer in American Indians and Alaska Natives. Cancer. Oct 15, 2007.