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CANCER SCREENING PART II

CANCER SCREENING PART II. AIMGP Seminar Series January 2004 Joo-Meng Soh Edited by Gloria Rambaldini. OBJECTIVES. Understand the concept of cancer screening and the controversies surrounding this topic To learn the Canadian screening guidelines for Breast and Colorectal cancer

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CANCER SCREENING PART II

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  1. CANCER SCREENINGPART II AIMGP Seminar Series January 2004 Joo-Meng Soh Edited by Gloria Rambaldini

  2. OBJECTIVES • Understand the concept of cancer screening and the controversies surrounding this topic • To learn the Canadian screening guidelines for Breast and Colorectal cancer • To be aware of other cancer screening guidelines available

  3. 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

  4. Case #1 • While on Team Medicine, you make the diagnosis of metastatic breast cancer in your 47 year old female patient • You think to yourself, “I wonder if she did Breast Self Examinations? Should she have received a mammogram? Would her cancer have been picked up earlier? Could she have been cured?”

  5. Guidelines Available

  6. Breast Cancer • Most frequently diagnosed cancer in women • In 2001, estimated: • 19,200 cases diagnosed • 5,500 deaths • 2nd leading cause of cancer death in women (after lung CA) Canadian Cancer Statistics 2001 http://66.59.133.166/stats/index.html

  7. Breast Cancer Statistics Risk of being Diagnosed with Breast Cancer Risk of Dying from Breast Cancer: 1 in 25

  8. Screening Maneuvers • Breast Self Examination (BSE) • Clinical Breast Examination (CBE) • Mammography

  9. Potential Benefits • Detection of Tumour at earlier stage • Improved Cosmetic result if found early • Reassurance if negative screening test

  10. Potential Harms • Radiation-induced Carcinoma from mammography • Est. risk of death from this is 8 per 100,000 women screened annually for 10 years beginning at age 40 • Unnecessary biopsies • Psychological stress of call-back • Possible false reassurance

  11. RCTs for BSE No reduction in breast cancer mortality or stage at diagnosis seen in two large scale on-going RCTs • Shanghai Trial (n=267 040 women) • Aged 31-64 • Results after first 5 years of follow-up • Russian/WHO Trial (n=122 471 women) • Aged 40-64 • Results after first 5 and 9 years of follow-up

  12. Breast Self-Examination ON THE OTHER HAND...... • RCTs showed a significant increase in: • number of physician visits for the evaluation of benign breast lesions • breast biopsy rates for benign lesions

  13. Breast Self Examination (BSE) • 1994 Canadian Task force on Preventive Health Care made BSE a Class C recommendation (insufficient evidence to recommend for or against BSE) • Due to recent trials, this screening tool now down-graded to class D (fair evidence to recommend that BSE be excluded from the periodic health exam)

  14. CBE & Mammography For Women Aged 50 - 69 • HIP (Health Insurance Plan) Trial • RRR of 0.55 in breast ca. mortality over 5 yrs • Swedish Trials • RRR of 0.29 in breast ca. mortality over 7-12 years follow-up • Canadian Trial comparing mammography over CBE • RRR of 0.03 (NS) at 7 years follow-up

  15. CBE & Mammography For Women Aged 50 - 69 Breast Cancer Screening with both CBE and mammography should be done for women aged 50-69 annually (Grade A Recommendation)

  16. CBE & Mammography For Women Aged 40 - 49 • CONFLICTING RESULTS!!! • Only one RCT designed specifically for women aged 40-49 did not have adequate power to exclude a clinically sig. benefit • Other RCT results are from post hoc subgroup analyses

  17. CBE & Mammography For Women Aged 40-49 • RRR of 18%-45% in breast cancer mortality at 10 years shown in 2 trials and 1 meta-analysis • No benefit was shown in 6 other trials • Recommendations: • Evidence does not support the use orexclusion of mammography for the periodic health exam in women aged 40-49 (Grade C)

  18. Back to the Case • “I wonder if she did BSEs” • Not currently recommended • “Should she have received a mammogram” • Unclear at this point in time; Women aged 40-49 should be informed of the risks and benefits of screening mammography and then assisted in making a decision” • “Would her cancer have been picked up earlier? Could she have been cured?” • Possibly....

  19. OTHER Guidelines  AAFP - American Academy of Family Physicians  ACOG - American College of Obstetricians and Gynecologists  ACS - American Cancer Society  CTFPHC Canadian Task force on Preventive Health Care  NIH - National Institutes of Health  USPSTF - U.S. Preventive Services Task Force

  20. Case #2 • During your GI rotation you consult on a 54 year old male with newly diagnosed metastatic colon cancer • Your team debates whether screening could have detected the cancer earlier? • Although the GI fellow swears by colonoscopies you wonder ‘what about all the hype regarding fecal occult testing vs sigmoidscopes vs barium enemas vs virtual c-scopes vs…”

  21. Guidelines Available

  22. COLORECTAL CANCER • Third most common cancer in Canada • In 2001, Estimated • New cases: 17,200 • Deaths: 6,400 Canadian Cancer Statistics 2001 http://66.59.133.166/stats/index.html

  23. Screening Tools • Fecal Occult Blood Testing • Sigmoidoscopy • Barium Enema • Colonoscopy

  24. Fecal Occult Blood (FOB) • Rationale – detect occult blood from cancers or large polyps • 3 consecutive stool samples at home • Evidence from 4 large-scale RCTs • Overall Sensitivity  25 - 50% • False positive rate  10% • Overall benefits are statistically sig. but small • Number needed to screen for 10 years to avert one death from colorectal cancer = 1173

  25. Sigmoidoscopy • May reduce the risk of death from Colorectal cancer (3 case control studies) • 3 RCTs suggest it may be superior in detecting adenomas and possibly cancer than FOBT (but no mortality data) • Potential Harms: • Bowel perforation in 1.4 per 10,000 exams

  26. Colonoscopy • Currently no direct evidence on mortality benefit from colonoscopy as a screening maneuver • Potential Harms: • Bowel perforation in 10 per 10,000 exams

  27. Comparison of all Three • Recent NEJM article: Aug. 23, 2001 “One-Time Screening for Colorectal Cancer with Combined FOBT and Examination of the Distal Colon”, Lieberman D et al • n = 2885 patients • All patients provided stool for FOBT, then underwent Colonoscopy (“sigmoidoscopy” was defined as examination of the rectum and sigmoid colon during colonoscopy)

  28. Comparison of all Three • Only 23.9% of patients with advanced neoplasia had a positive FOBT • Sigmoidoscopy identified only 70.3% of all subjects with advanced neoplasia • Combined FOBT and sigmoidoscopy identified only 75.8% of subjects with advanced neoplasia In other words, combined FOBT and sigmoidoscopy would have missed 25% of the colorectal cancers

  29. Canadian Recommendations • Good evidence to include annual or biennial FOBT (Grade A Recommendation) • Fair evidence to include Flexible Sigmoidoscopy (Grade B Recommendation) • Insufficient evidence to make recommendations about whether only one or both tests should be performed (Grade C) • Insufficient evidence to include or exclude colonoscopy as initial screening test Grade C) Colorectal Cancer Screening – Recommendations from the Canadian Task force on Preventive Health CareCMAJ 2001; 165(2): 206 - 208

  30. Other Guidelines Outdated • AAFP - American Academy of Family Physicians  ACOG - American College of Obstetricians and Gynecologists  ACS - American Cancer Society  AMA - American Medical Association  AGA - American Gastroenterological Association  CTFPHC - Canadian Task Force on Preventive Health Care  USPSTF - U.S. Preventive Services Task Force

  31. Back to the Case • Screening can result in the reduction in CRC related mortality • Recommendations thus far include routine FOBT and sigmoidoscopy • Routine colonoscopy is not supported by good evidence at present • Like all screening tests…patient counseling will guide you and the patient

  32. Other References • Cancer Screening Guidelines, American Family Physician 2001, 63(6):1101-1112 • Summarizes in table format the guidelines published by multiple organizations • Preventive Health Care, 2001 update: screening mammography among women aged 40-49 years at average risk of breast cancer, CMAJ 2001; 164(4): 469-76 • Preventive Health Care, 20001 update: Should women be routinely taught BSE to screen for breast cancer, CMAJ 2001; 164(13): 1837-46

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