Risk of Metachronous Advanced Neoplasia After Colonoscopy in Patients With Different Index Findings.

Abstract

Objective: Patients undergoing colonoscopy are at risk of developing metachronous advanced neoplasia (AN). This study explores risk factors of metachronous AN and refines risk stratification based on different index findings.

Methods: This retrospective cohort study included patients undergoing multiple colonoscopies performed by experienced endoscopists at a major tertiary hospital in China in 2012-2023. Cox regression, adjusted for covariates, estimated the risk of metachronous AN. Cumulative hazard was determined using Kaplan-Meier estimation. Multiple sensitivity analyses validated the impact of risk factors.

Results: A total of 3638 patients was included. In the index nonadvanced adenoma (NAA) group, covariate-adjusted Cox regression showed proximal adenomas (hazard ratio [HR], 2.99; 95% confidence interval [CI], 1.20-7.44), adenomas ≥ 6 mm (HR, 3.29; 95% CI, 1.49-7.26), and ≥ 3 adenomas (stratified by time horizons: HR, 4.05; 95% CI, 1.25-13.10) were associated with increased risk of metachronous AN. In the group with non-significant findings at index colonoscopy, age ≥ 50 years (HR, 2.19; 95% CI: 1.36-3.51), family history of colorectal cancer (HR: 5.55; 95% CI: 2.96-10.44), and male sex (HR: 2.45; 95% CI: 1.61-3.73) were associated with increased risk of metachronous AN. Survival analysis revealed that patients with these risk factors reached reference risk for developing metachronous AN much earlier.

Conclusions: Based on a Chinese population, we identified independent risk factors for metachronous AN across different baseline diagnostic subgroups, facilitating personalized risk stratification for high-risk patients. Risk profiles should be considered when defining the optimal surveillance interval for colonoscopy.