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Screening for Colorectal Cancer

Screening for Colorectal Cancer. Cancer Symposium: Measuring the Benefits of Screening and Treatment October 2007. Why should we screen of colon and rectal cancer?. Because it is common. Third most common cancer in Canada 20,400 new cases Second most lethal 8,700 deaths

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Screening for Colorectal Cancer

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  1. Screening for Colorectal Cancer Cancer Symposium: Measuring the Benefits of Screening and Treatment October 2007

  2. Why should we screen of colon and rectal cancer?

  3. Because it is common • Third most common cancer in Canada • 20,400 new cases • Second most lethal • 8,700 deaths • The most lethal among non smokers

  4. Natural History • The polyp cancer sequence • Surgical and endoscopic techniques

  5. Because we can

  6. Screening for CRC • No symptoms • Average risk • High risk

  7. Screening for CRC • Average risk individual • When to start? • Age 50 • Incidence 1:500 age 40 -49 y • 1:125 50-59 y • 1:50 60-69 y

  8. Fecal Occult Blood Testing • The only screening test with Level I evidence that it can decrease the mortality from CRC • NEJM 1993 Minnesota Trial • Lancet 1996 European Study • 18 yr follow-up from the Minnesota Trial shows an 21% mortality reduction in the screening cohort

  9. FOBT • “2 samples from each of 3 consecutive stool samples, with dietary restrictions if using a guaiac based test” • Any positive result followed up with colonoscopy

  10. FOBT • How often? • High false positive rate • Significant false negative rate

  11. Canadian Task Force on Preventative Health • “the number needed to screen for 10 years to avert one death from colorectal cancer is 1173”

  12. Flexible Sigmoidoscopy: The Good • The scope is 50 cm long • Easier • Perforation rate is low • Most cancers (in average risk individuals) are within 50 cm • Biopsy and polypectomy is possible

  13. Flexible Sigmoidoscopy: The Bad • The scope is 50 cm long • Perforation rate is 1.4 per 1000 • Prep is necessary

  14. Flexible Sigmoidoscopy • Good for 5 years • ? Should one do a full colonoscopy if a low risk polyp is found in the distal colon • Lancet 2002 UK RCT found an 80% mortality reduction form CRC

  15. Double Contrast Barium Enema • No randomized trails that evaluate this as a screening tool for average risk individuals • It does not see the rectum well • It misses 50% of polyps < 1.0 cm • Q 5 years

  16. Combinations • DCBE and Flex sig • No data • FOBT and Flex sig • Limited data

  17. Colonoscopy: The Good • Although there is no evidence…… • Allows diagnostic biopsy and endoscopic removal of polyps • Shelf life of 10 years in average risk individuals

  18. Colonoscopy: The Bad • Highly trained personnel • Resource intense • Expensive • Do we have the capacity?

  19. Colonoscopy: The Ugly • Prep • Perforation risk • 1:1000 all comers • 1:2000 screening • 1:15000 mortality

  20. Emerging Technologies • Fecal DNA analysis • Virtual colonoscopy

  21. Virtual Colonoscopy

  22. Emerging Technologies • Fecal DNA analysis • Virtual colonoscopy • Micro array gene expression analysis

  23. High Risk Individuals • Good news and bad news • Family History • FAP • HNPCC • IBD

  24. Family history • 1 first degree relative < 60 with CRC or polyp disease or • 2 first degree relatives with CRC at any age • Begin at age 40, or 10 years younger than the youngest relative and continue q 5 years

  25. Family history • 1 First degree relative > 60 with CRC or polyp disease or • 2 second degree relatives with CRC at any age • Should be screened as an average risk but beginning at age 40

  26. Family History • 1 second degree relative or any number of third degree relatives should be screened as average risk

  27. Familial Adenomatous Polyposis (FAP) • Flexible sigmoidoscopy at age 14 • +/- genetic testing

  28. Hereditary Non-polyposis Colon Cancer (HNPCC) • Amsterdam II Criteria • 3 relatives (at least I first degree) • Successive generations • One with Ca <50 • FAP r/o

  29. HNPCC • Colonoscopy q 2 years • +/- genetic testing for MMR gene mutation • +/- genomic analysis of tissue for micro satellite instability

  30. Patients with Inflammatory Bowel Disease • Same for UC or Crohns • 8 years after the onset of disease in pancolitis • 15 years after onset in Left sided disease • Colonoscopy q 1 - 2 years

  31. Patients with a history of Polyps • Advanced adenoma • >10 mm • Villous architecture • HGD • >2 polyps less than 10 mm • AGA……3 years • CAG…….clinical judgment

  32. Patients with a history of polyps • One or two polyps , each less than or = 10 mm • 5 years

  33. Summary • Screening is good • Begin at age 50 in average risk individuals • Options • FOBT +/- colonoscopy • colonoscopy • High risk individuals should have colonoscopy

  34. Questions

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