CANCER SCREENING PART I AIMGP Seminar Series January, 2004 Joo-Meng Soh Edited by Gloria Rambaldini

CASE #1 Your father has just turned 50 years old and his family doctor is recommending prostate cancer screening tests. He has been reading the newspapers and came across the following article: Toronto Star, Dec. 31, 2001

CASE #1 a) No... the health care system can’t afford it b) Yes – go for a Digital Rectal Exam c) Yes – go for a PSA test d) Yes – go for a DRE and a PSA e) Don’t know – I haven’t been through AIMGP Cancer Screening Guidelines Part I yet.... He asks you if he should be screened and what tests he should undergo... You tell him:

OBJECTIVES Understand the concept of cancer screening and the controversies surrounding this topic To learn the Canadian screening guidelines for Prostate and Cervical cancer To be aware of other cancer screening guidelines available

Principles of Cancer Screening Screening of asymptomatic individuals to detect early cancers which may be curable Use of diagnostic tests of high sensitivity Diagnostic tests are suitable to the patient Natural history of disease can be changed by intervention Proposed early treatment should be beneficial and not harmful to the patient

Guidelines Available Website:

Guidelines Available

Prostate Cancer 2 nd most frequent cause of cancer- related deaths among males Rapid rise in incidence over age 60 Lifetime risk of developing prostate cancer=16 %; risk of dying 3% Many cases not clinically evident: –at autopsy prostate CA in one-third of men 80 Prostate CA grows slowly: most men die of other causes

Prostate Cancer Canadian Statistics: Estimated New cases for 2001: Estimated Deaths for 2001: 4300 Canadian Cancer Statistics 2001 Website:

Options for Screening Digital Rectal Examination Prostate-Specific Antigen (PSA) Trans-Rectal UltraSound (TRUS) –not recommended as a screening tool  primary use is to guide biopsies

Digital Rectal Examination Sensitivity Poor 40-50% of cancers are out of reach Inter-rater reliability low-moderate PPV 15-30%, NPV even lower NOTE: Since Gold Standard Test is prostatectomy or extensive biopsy, Sens. & Spec. cannot be accurately determined  Positive and Negative Predictive Values are used instead

Prostate Specific Antigen Produced by epithelial cells of prostate Levels > 4.0 ng/mL “suspicious” Physicians' Health Study (22,000 men with long-term follow-up) –sensitivity of a single baseline PSA >4.0 ng/mL approximately 73% for any prostate cancer – 87% for aggressive cancers –Canadian data suggests high false positive rates

Prostate Specific Antigen Positive Predictive Value: –If PSA 4-10:22% –If PSA >10:40-60% Conditions which increase PSA levels –BPH, DRE –TRUS, Biopsy –Prostatic infection, recent ejaculation

Prostate Specific Antigen As PSA levels increase: –Odds of cancer increase –Odds of extra-capsular or metastatic disease increase –Odds of “cure” decrease if it is cancer

PSA - Pros Detect cancer early, while still curable

PSA - Cons No evidence for a reduction in morbidity or mortality Positive test may result in unnecessary tests and treatments

PSA – Cons Treatment of early stage cancer may have no impact on overall survival Even combined with DRE, PPV not substantially higher (20%) Possible harms with treatment (prostatectomy or radiation therapy): –impotence, urinary incontinence, peri-operative morbidity/mortality

Prostate Screening Guidelines Variety of Recommendations exist:  AAFP American Academy of Family Physicians  ACP-ASIMAmerican College of Physicians-American Society of Internal Medicine  ACS American Cancer Society  AUA American Urological Association  AMA American Medical Association  CTFPHC Canadian Task Force on Preventive Health Care  USPSTF U.S. Preventive Services Task Force

Recommendations Canadian Task Force on Preventative Health Care: “ Based on the absence of evidence for effectiveness of therapy and the substantial risk of adverse effects of associated with such therapy and the poor predictive value of screening tests, there is at present insufficient evidence to support wide-spread initiatives for the early detection of prostate cancer.”

Recommendations ACP-ASIM gives a pragmatic compromise: “Physicians should describe potential benefits and known harms of screening, diagnosis, and treatment; listen to the patient’s concerns, then individualize the decision to screen”

Counseling Patients Prostate Cancer is an important health problem Benefits of Screening are unproven DRE & PSA can have false positives and false negatives Probability of further invasive evaluation is high (around 15%)

Counseling Patients If a tumour is found, aggressive therapy (along with its risks/complications) is necessary to realize any benefit Early detection may save lives and avert future cancer-related illness

Counseling Patients Ministry of Health and Longterm Care provides information for patients: Available through ICES Website:

Back to the Case Review the data Discuss the options with the family doctor Then make an informed decision on whether or not to undergo screening

CASE #2 62 y.o. widowed female with two healthy children She says, “I’m 62 years old now and no longer sexually active. My last two PAP tests were negative.” She asks ”Do I really need another one? Will this ever end???”

CASE #2 You tell her: a) No – you are too old for it now b) No – because your last two were negative c) Yes – every year d) Yes – every 3 years e) I don’t know yet.....but I’ll tell you in 5 minutes (after the end of this seminar)

Guidelines Available

Cervical Cancer 11 th most common cancer among women in Canada Canada, 1993: –1300 women developed cervical cancer –400 women died of the disease Canadian Statistics: Estimated New cases (2001): 1450 Estimated Deaths (2001): 420

Cervical Cancer Risk Factors –early age at first sexual intercourse (<17y/o) –multiple sexual partners (>2) –smoking –low socioeconomic status –HPV Infection (Types 16, 18, 31, 39, 45, 56, 58, 59, 68) –Hx STDs –Hx other lower genital tract neoplasia –Radiation –Immunosuppression –OCPs

Cervical Cancer Screening Papanicolaou Smear Test High False Neg. Rate: up to 25% –Sampling error (failure of MD to obtain malignant cells from the cervix; failure to take samples from the squamo-columnar junction) –Lab Error Note: testing for HPV not currently recommended

The Evidence No RCT’s- due to the widespread use of this screening test Only Cohort and Case-control studies provide evidence for a reduction in the incidence of invasive disease Optimal frequency of screening is less known

Cervical Cancer Screening Guidelines  AAFP:American Academy of Family Physicians  ACOG:American College of Obstetricians and Gynecologists  ACS:American Cancer Society  AMA:American Medical Association  CTFPHC:Canadian Task force on Preventive Health Care  USPSTF:U.S. Preventive Services Task Force

Canadian Guidelines Addendum Consider screening more frequently in high risk women (due to the high FN rate and the variable rate of progression of disease) The largest group of women at risk of dying from cervical cancer are those who have never been screened before

BACK TO THE CASE Continue screening every 3 years until the age of 69 The Pap tests will eventually end....

Principles of Cancer Screening Screening of asymptomatic individuals to detect early cancers which may be curable Use of diagnostic tests of high sensitivity Diagnostic tests are suitable to the patient Natural history of disease can be changed by intervention Proposed early treatment should be beneficial and not harmful to the patient