The Risk of Metachronous Advanced Colorectal Neoplasia Rises in Parallel with an Increasing Number of High-Risk Findings at Baseline

BACKGROUND/AIMS: Colorectal adenomas that are ≥10 mm have villous histology or high-grade dysplasia, or that are associated with ≥3 adenomas are considered high-risk for metachronous advanced neoplasia. We evaluated the cumulative incidence of metachronous advanced neoplasia according to the total number of high-risk findings detected on baseline colonoscopy. METHODS: This was a retrospective cohort study performed in 862 patients who underwent removal of colorectal adenomas between 2005 and 2009. At least one surveillance colonoscopy had been conducted at Konkuk University Medical Center, Seoul, Korea. RESULTS: The cumulative incidence of metachronous advanced neoplasia in patients with 0, 1, 2, and 3–4 high-risk findings at 1 year were 0.7%, 1.3%, 2.8%, and 8.0%; at 3 years, those were 5.9%, 11.9%, 15.5%, and 24.7%; and at 5 years, those were 8.5%, 18.7%, 26.3%, and 37.2%, respectively. In a multivariate model, the risk of metachronous advanced neoplasia was significantly higher for the multiple high-risk findings group when compared with the 0 high-risk findings group (1 high-risk (+): hazard ratio, 1.86 [95% confidence interval, 1.00–3.44]; 2 high-risk (+): 1.84 [0.88–3.84]; and 3–4 high-risk (+): 3.29 [1.54–7.01]; p(trend)=0.020). CONCLUSIONS: The presence of overlapping multiple high-risk findings was associated with an increased risk of advanced neoplasia during surveillance.