Role of Colonoscopy and Polyp Characteristics in Colorectal Cancer After Colonoscopic Polyp Detection A Population-Based Case-Control Study

Background: Studies have identified characteristics of adenomas detected on colonoscopy to be predictive of adenoma recurrence. Objective: To assess the role of both colonoscopy-related factors and polyp characteristics on the risk for colorectal cancer after colonoscopic polyp detection. Design: Population-based case-control study (3148 case participants and 3274 control participants). Setting: Rhine-Neckar region of Germany. Patients: Case and control participants with physician-validated detection of polyps (other than hyperplastic polyps) at a previous colonoscopy in the past 10 years. Measurements: Detailed history and results of previous colonoscopies were obtained through interviews and medical records. Case and control participants were compared according to colonoscopy-related factors (incompleteness, poor bowel preparation, incomplete removal of all polyps, and no surveillance colonoscopy within 5 years) and polyp characteristics (>= 1 cm, villous components or high-grade dysplasia, >= 3 polyps, and >= 1 proximal polyp). Odds ratios (ORs) and attributable fractions were derived by using multiple logistic regression and the Levin formula. Results: 155 case participants and 260 control participants with physician-validated polyp detection in the past 10 years were identified. The following characteristics were significantly more common among case participants than among control participants: not all polyps completely removed (29.0% vs. 9.6%; OR, 3.73 [95% CI, 2.11 to 6.60]), no surveillance colonoscopy within 5 years (26.5% vs. 11.5%; OR, 2.96 [CI, 1.70 to 5.16]), and detection of 3 or more polyps (14.2% vs. 7.3%; OR, 2.21 [CI, 1.07 to 4.54]). Odds ratios ranged from 1.12 to 1.42 and CIs included 1.00 for all other variables. Overall, 41.1% and 21.7% of cancer cases were statistically attributable to colonoscopy-related factors and polyp characteristics, respectively. Limitation: This was an observational study with potential for residual confounding and selection bias. Conclusion: Colonoscopy-related factors are more important than polyp characteristics for stratification of colorectal cancer risk after colonoscopic polyp detection in the community setting.