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Screening for Colorectal Cancer, 2008 Robert S. Sandler, M.D., M.P.H. Professor of Medicine Epidemiology University

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Screening for Colorectal Cancer, 2008 Robert S. Sandler, M.D., M.P.H. Professor of Medicine Epidemiology University

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    2. US Cancer Deaths, 2008

    3. New guidelines - 2008

    4. ACS Screening Recommendations - 2008 Tests That Detect Adenomatous Polyps and Cancer Flexible sigmoidoscopy every 5 years, or Colonoscopy every 10 years, or Double-contrast barium enema every 5 years, or Computerized tomographic colonography every 5 years Tests That Detect Cancer Annual guaiac-based FOBT with high test sensitivity Annual FIT test with high sensitivity for cancer Stool DNA test with high sensitivity for cancer, interval unknown

    10. FOBT

    12. What to do when FOBT positive Colonoscopy: the purpose of FOBT is to identify individuals who might have cancer. If any of the six windows is positive, the patient should have a complete colon exam using colonoscopy

    13. Sensitive guaiac-based test

    15. Digital FOBT 3121 asymptomatic patients 50-70 years old 2665 had digital FOBT and complete colonoscopy For advanced neoplasia digital FOBT: Sensitivity 4.9% Negative likelihood ratio 0.98 “negative likelihood ratio” (LR-) tells us how much to decrease it I f the test is negative. The formula for calculating the likelihood ratio is: “negative likelihood ratio” (LR-) tells us how much to decrease it I f the test is negative. The formula for calculating the likelihood ratio is:

    16. Digital FOBT A negative result on a test for FOB in digital rectal sample does not change the odds of advanced colonic neoplasia. Physicians should not rely on FOBT performed on a single sample of stool

    17. Digital FOBT

    18. Fecal Immune Tests (FIT)

    21. Fecal Immune Tests Advantages of FIT (fecal immune tests) Superior sensitivity and specificity Uses antibodies specific for human globin and specific for colorectal (not upper) bleeding Not affected by diet or medications May improve patient compliance

    24. Fecal DNA

    27. Sigmoidoscopy Odds of having had at least one screening sigmoidoscopy during the 10-yr. period before the diagnosis of fatal cancer in the case subjects CASE ODDS SUBJECTS CONTROLS RATIO (n=261) (n=868) (95% CI) Cancer within reach of sigmoidoscope 23 (8.8%) 210 (24.2%) 0.30 (0.19-0.48) Cancer above reach of sigmoidoscope 56 (22.9%) 67 (25.0%) 0.80 (0.54-1.19)

    28. Combined sigmoidoscopy and FOBT

    29. Combined FOBT and sigmoidoscopy

    30. Colonoscopy

    31. National Polyp Study

    32. Colonoscopy advantages Examines entire colon High sensitivity High specificity Able to remove polyps If normal can wait 10 years until next exam Widely available Cost effective

    33. Screening steps Two step Hemoccult Fecal immune Stool DNA Barium enema Sigmoidoscopy CT colonography

    35. Those practical recommendations, recently published in gastroenterolog, are shown here. Close relatives with colorectal cancer or adenomatous polyps should have the same screening as everybody else but starting earlier -at age 40 (remember in the previous slide the curves were similar but left shifted). If the close relative was diagnoses with cancer before age 55 or adenoma before age 60, need to take special efforts for screening. May prefer colonoscopy. Those practical recommendations, recently published in gastroenterolog, are shown here. Close relatives with colorectal cancer or adenomatous polyps should have the same screening as everybody else but starting earlier -at age 40 (remember in the previous slide the curves were similar but left shifted). If the close relative was diagnoses with cancer before age 55 or adenoma before age 60, need to take special efforts for screening. May prefer colonoscopy.

    36. During the course of follow up about 500 colon cancers developed in cohort members. As you can see from this graph, those individuals who had a family history of colon cancer were more likely to develop colon cancer themselves compared to those with no family history. They also developed colon cancer at a younger age. The relative risk was 1.72, similar to what we saw in the National Polyp Study. Based on these two studies we see that if a person has a first degree relative with an adenoma or cancer, they are about twice as likely to get cancer, and that they get cancer at an earlier age than the general population. How can we translate that information into practical recommendations.During the course of follow up about 500 colon cancers developed in cohort members. As you can see from this graph, those individuals who had a family history of colon cancer were more likely to develop colon cancer themselves compared to those with no family history. They also developed colon cancer at a younger age. The relative risk was 1.72, similar to what we saw in the National Polyp Study. Based on these two studies we see that if a person has a first degree relative with an adenoma or cancer, they are about twice as likely to get cancer, and that they get cancer at an earlier age than the general population. How can we translate that information into practical recommendations.

    39. CT Colonography

    40. CTC advantages and disadvantages Advantages Safe Examines both sides of bowel folds Precisely localizes lesions Can examine proximal colon when colonoscopy incomplete or distal obstruction Disadvantages Bowel prep Gas distension Radiation Time consuming Diagnostic only

    41. Cost effectiveness of CTC

    42. Cost effectiveness of CTC CT colonography is more expensive and generally less effective than optical colonoscopy. CT colonography can be reasonably cost-effective when the diagnostic accuracy of CT colonography is high and if costs are about 60% of those of optical colonoscopy. Overall, CT colonography technology will need to improve its accuracy and reliability to be a cost-effective screening option.

    43. How good is CTC?

    44. Flat polyps

    46. Flat adenoma missed on CTC

    48. Computer-aided detection

    49. Computer-aided detection

    50. New tests

    52. Take home messages Don’t screen before age 50 Screening options: FOBT, flex sig, colonoscopy, FIT, CTC, DNA Don’t do FOBT on digital samples Evaluate positive FOBT with colonoscopy Fecal immune test may be better than guaiac Colonoscopy is the definitive (one step) test to detect colorectal neoplasia

    53. These tests can be recommended Colonoscopy CT Colonography These tests are not ready or are not good enough Barium enema Sensitive FOBT FIT Test – may not be better than sFOBT Stool DNA test Sigmoidoscopy New Guidelines

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