Colorectal Cancer Screening: Colonoscopy, Potential and Pitfalls Disclosures: None Jonathan P. Terdiman, M.D. Professor of Clinical Medicine University of California, San Francisco CRC: still a major public health problem Cumulative Mortality from Colorectal Cancer in the General Population, as Compared with the Adenoma and Nonadenoma Cohorts. 1 million cases per year worldwide and ½ million deaths USA 4 th most common cancer ~ 150, 000 cases per year 2 nd most common cause of cancer death ~ 50, 000/yr Lifetime risk is 3-6% Zauber AG et al. N Engl J Med 2012;366:687-696.
Screening Options FOBT q year Flexible sigmoidoscopy q 5 yrs FOBT and Flexible sigmoidoscopy Colonoscopy q 10 years CT colonography q 5 years Screening Colonoscopy Compelling indirect evidence that this is the best test FOBT studies Flex Sig Studies Polypectomy Studies Cohort studies Screening Colonoscopy: VA Cooperative Study (Lieberman et al. NEJM, 2000) Advanced adenoma in 7.9% Cancer in 1.0% 73% with Stage I or II disease 20% with Stage III and 6% with Stage IV 44% of patients with advanced neoplasia would have been missed by flex sig first screen 30% missed by sig + FOBT Colonoscopy in the real world: The Polyp Prevention Trials 9 studies with > 20, 000 years of patient follow-up Incidence of CRC = 1.7-2.4/1, 000 person-years Incidence is equivalent to general population and 4 x that in National Polyp Study!!! Gastroenterology 2005;129:34-41 Gastrointest Endosc 2005;61:385-91
Impact of colonoscopy on CRC death Baxter NN. Ann Int Med, 2009 10, 292 CRC deaths and 51, 940 controls among 1.2 million Canadians, 1996-2001 OR for death with colonoscopy = 0.69 Left sided cancers, OR = 0.33 Right sided cancer, OR = 0.99 Incomplete Exam Gastro, 2007 Pop-based study in Canada > 300, 000 exams, 13% incomplete Risk Factors Older age Women Prior operation Test in MD office Missed Cancers Gastro, 2007 AN: Left vs. Right Polyps Gupta S, et al. Clinical Gastroenterology and Hepatology 2012; 10:1395-1401. Cancers diagnosed within 3 yrs of colonoscopy Risk Factors Older age Diverticular disease Right sided cancer Internist/Family MD doing the test Test in a MD office
Flat & Depressed Polyps Soetikno R, Jama 2008 1819 exams, use of dye spray to confirm Prevalence = 9.4% (95% CI, 8.1-10.8) OR for cancer = 9.8 Incomplete Polyp Resection Pohl H, Gastroenterology 2012 Prospective study of 1427 patients who underwent colonoscopy 10% inadequately resected Wide range by MD (6.5-23%) Risk Factors Large size: 17% for > 10 mm Serrated polyps: 31% Less than 20 polypectomies/year Advanced Polypectomy Holt BA, Clin Gastro Hepatol, 2012 Biological Variability 51 interval cancers within 5 years of colonoscopy MSI in 30.4% of interval cancers versus 10.3% of others (p = 0.003) Interval cancers 3.7 x more likely to be MSI 27% of interval cancers at previous polypectomy segment Interval cancers 3 times more likely to be R sided Farrar WD Gastro, 2006 Sawhney MS Clin Gastro Hepatol, 2006
Doing colonoscopy well Barclay RL NEJM, 2007 Mean adenoma detection rate according to colonoscopic withdrawal times 12 endoscopists doing over 2000 screening exams Range of adenoma detection 9.4% to 32.7% Range of scope withdrawal times 3.1 to 16.8 minutes Detection rate < versus > 6 minutes 11.8% versus 28.3% for any adenoma (p < 0.001) 2.6% versus 6.4% for advanced adenoma (p = 0.005) Cumulative Hazard Rates for Interval Colorectal Cancer, According to the Endoscopist's Adenoma Detection Rate (ADR). Kaminski MF et al. N Engl J Med 2010;362:1795-1803. Benchmarks for GOOD Colonoscopy Adenoma Detection Rate > 25% men, 15% women PLCO data: 2.4 fold risk of interval cancer in those with lowest quartile of ADR vs. highest Documentation of Prep 100% Cecal Intubation >/= 95% Recent population-based study in Canada rate was only 87% Withdrawal Times >/= 6 minutes?
Colonoscopy done well Brenner, Ann Int Med, 2011 Population-based case-control study in Germany 1688 CRC cases and 1932 controls Colonoscopy within 10 years 77% risk reduction for CRC 84% for left-sided cancer 66% for right-sided