Long-term cumulative incidence of metachronous advanced colorectal neoplasia after colonoscopy and a novel risk factor: a cohort study

neoplasia, including both advanced colorectal adenoma (>= 10 mm, or with villous or high-grade dysplasia) and colorectal cancer, are critical for surveillance strategies. The aim of this study was to determine the cumulative incidence of metachronous advanced colorectal neoplasia and its risk factors. Methods A retrospective cohort study was conducted on 6720 consecutive individuals who underwent general health checkups and colonoscopy. Colorectal adenomas at initial colonoscopy were categorized as low-risk (1-2 small [<10 mm] tubular adenomas) or high-risk adenoma (>= 3 tubular adenomas of any size; at least one adenoma >= 10 mm; or villous adenoma or adenoma with high-grade dysplasia). Kaplan-Meier estimates and hazard ratio by Cox-proportional hazard regression were calculated. Results The cumulative incidence (95% confidence interval [CI]) of metachronous advanced colorectal neoplasia at 5 and 10 years was 5.7% [4.6-7.1], and 11% [8.9-14] in the low-risk adenoma group, and 10% [8.6-13], and 17% [14-21] in high-risk adenoma group, respectively. Adjusted hazard ratio [95% CI] of low-risk adenoma (vs. no colorectal adenoma), high-risk adenoma (vs. no colorectal adenoma), current smoking and positive fecal immunochemical test were 1.34 [1.04-1.74], 1.94 [1.48-2.55], 1.55 [1.2-2.02] and 1.69 [1.35-2.1], respectively. Adjusted hazard ratio [95% CI] of positive fecal immunochemical test was 1.88 [1.29-2.74] in those with normal colonoscopy. Conclusions Both low-risk and high-risk adenomas confer substantial risk for metachronous advanced colorectal neoplasia at 10 years. Positive fecal immunochemical test was a significant risk factor for metachronous advanced colorectal neoplasia despite normal colonoscopy. Copyright (C) 2021 Wolters Kluwer Health, Inc. All rights reserved.

Automated summary

The study found that risk factors for colorectal adenomas include size and degree of dysplasia. Both low-risk and high-risk adenomas confer increased risk for metachronous colorectal neoplasia at 10 years. Positive fecal immunochemical test is a significant risk factor for metachronous advanced colorectal neoplasia despite normal colonoscopy.