Aim: To evaluate colorectal cancer risk among patients with sporadic duodenal neoplasia using a case-control protocol.
Methods: Cases were 35 patients referred for the management of sporadic duodenal adenoma and who underwent colonoscopy. Colonoscopy findings among cases were compared with those from a control group matched for age and sex (two controls per case) without duodenal adenoma. Colonoscopy findings were categorized as adenoma, advanced adenoma, cancer or advanced neoplasia. The two groups were compared using the chi-squared test. Odds ratio and 95% confidence intervals were calculated.
Results: Colorectal adenoma was present in 31% of cases vs. 24% of controls, advanced neoplasia in 29% vs. 4%, advanced adenoma in 23% vs. 3% and adenocarcinoma in 6% vs. 1%. The relative risks of advanced colorectal adenoma and advanced colorectal neoplasia in cases were 10.1 (95% CI: 1.8-100.1, P = 0.003) and 8.9 (95% CI: 2.1-53.3, P = 0.001), respectively.
Conclusions: The relative risk of advanced colorectal adenoma and advanced neoplasia in cases was nine- to 10-fold that among controls. Patients with sporadic duodenal adenoma represent a high-risk group for advanced colorectal neoplasia and should therefore undergo complete colonoscopy.