Assessing individual risk for high-risk colorectal adenoma at first-time screening colonoscopy

Assessing risk of colorectal adenoma at first-time colonoscopy that are of higher likelihood of developing advanced neoplasia during surveillance could help tailor first-line colorectal cancer screening. We developed prediction models for high-risk colorectal adenoma (at least one adenoma 1 cm, or with advanced histology, or 3 adenomas) among 4,881 asymptomatic white men and 17,970 women who underwent colonoscopy as their first-time screening for colorectal cancer in two prospective US studies using logistic regressions. C-statistics and Hosmer-Lemeshow tests were used to evaluate discrimination and calibration. Ten-fold cross-validation was used for internal validation. A total of 330 (6.7%) men and 678 (3.8%) women were diagnosed with high-risk adenoma at first-time screening colonoscopy. The model for men included age, family history of colorectal cancer, BMI, smoking, sitting watching TV/VCR, regular aspirin/NSAID use, physical activity, and a joint term of multivitamin and alcohol. For women, the model included age, family history of colorectal cancer, BMI, smoking, alcohol, beef/pork/lamb as main dish, regular aspirin/NSAID, calcium, and oral contraceptive use. The C-statistic of the model for men was 0.67 and 0.60 for women (0.64 and 0.57 in cross-validation). Both models calibrated well. The predicted risk of high-risk adenoma for men in the top decile was 15.4% vs. 1.8% for men in the bottom decile (Odds Ratio [OR]=9.41), and 6.6% vs. 2.1% for women (OR=3.48). In summary, we developed and internally validated an absolute risk assessment tool for high-risk colorectal adenoma among the US population that may provide guidance for first-time colorectal cancer screening. What's New? Population screening has dramatically reduced mortality rates for colorectal cancer (CRC) in the U.S. However, colonoscopy is expensive, and healthcare resources need to be more efficiently allocated. In this study, the authors developed and validated a comprehensive risk-assessment tool for high-risk colorectal adenoma. This tool, which includes a list of risk factors, may allow first-line colorectal cancer screening to identify people who are at increased risk. These people could then be encouraged to undergo colonoscopy, and to alter their behavior and lifestyle factors to lower their risk.