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

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.

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.

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.

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.