Risk of developing advanced colorectal neoplasia after removing high-risk adenoma detected at index colonoscopy in young patients: A KASID study

Background and Aim: Advanced adenoma (>10 mm in diameter, villous structure, or high-grade dysplasia) in young patients may have different characteristics and prognosis compared with those in older patients. We aimed to compare the incidence of colorectal neoplasms in young patients with older patients after removing high-risk adenoma (advance adenoma or ≥3 adenomas). Methods: A retrospective, multicenter study was conducted at 13 university hospitals in Korea. The 1479 patients who removed high-risk adenoma at index colonoscopy and followed by surveillance colonoscopy ≥2.5 years after were included. The cumulative incidence of overall and advanced colorectal neoplasms was compared according to the age groups (group 1: <50years, group 2: 50-70 years, and group 3: ≥70 years). Results: The prevalence of advance adenoma detected at index colonoscopy was significantly higher in group 1 than in groups 2 and 3 (85.4%, 78.1%, and 77.2%, respectively; P=0.035). The 5years cumulative incidence of overall and advanced colorectal neoplasms were 61.9%, 67.9%, and 74.7% (P<0.001), and 11.7%, 17.9%, and 27.1% (P=0.001) in groups 1, 2, and 3, respectively. In multivariate analysis, age >70 years was a significant risk factor for developing overall (hazard ratio [HR] 1.41, 95% confidence interval [CI] 1.12-1.82, P=0.004) and advanced colorectal neoplasms (HR=2.56, 95% CI 1.43-4.59, P=0.002). Conclusion: The cumulative incidence of overall and advanced colorectal neoplasms was significantly higher in older patients than in young patient groups. Age was a significant risk factor for developing colorectal neoplasms after removing high-risk adenoma.