Ten or More Cumulative Lifetime Adenomas Are Associated with Increased Risk for Advanced Neoplasia and Colorectal Cancer

Background: Colorectal cancer (CRC) screening guidelines recommend frequent colonoscopies and consideration of genetic testing in individuals with ≥10 cumulative adenomas. However, it is unclear how these guidelines apply to routine practice. Aims: We estimated the proportion of participants found to have ≥10 cumulative adenomas in a screening population and described their outcomes of advanced neoplasia (AN), CRC, and extra-colonic malignancy. Methods: We performed a secondary analysis of VA CSP#380, which includes 3121 veterans aged 50–75 who were followed up to 10 years after screening colonoscopy. We calculated the cumulative risk of ≥10 cumulative adenomas by Kaplan–Meier method. We compared baseline risk factors in those with and without ≥10 cumulative adenomas as well as the risk for AN (adenoma ≥1 cm, villous adenoma or high-grade dysplasia, or CRC) and extra-colonic malignancy by multivariate logistic regression. Results: The cumulative risk of ≥10 cumulative adenomas over 10.5 years was 6.51% (95% CI 4.38%–9.62%). Age 60–69 or 70–75 at baseline colonoscopy was the only factors associated with the finding of ≥10 cumulative adenomas. Compared to those with 0–9 cumulative adenomas, participants with ≥10 cumulative adenomas were more likely to have had AN (OR 17.03; 95% CI 9.41–30.84), including CRC (OR 7.00; 95% CI 2.84–17.28), but not extra-colonic malignancies. Conclusions: Approximately 6.5% of participants in this screening population were found to have ≥10 cumulative adenomas over 10.5 years, which was uncommon before age 60. These participants were found to have AN and CRC significantly more often compared to those with lower cumulative adenomas.