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.