Risk factors for metachronous adenoma in patients with stage I/II colorectal cancer after radical surgery

Background: It is important to implement a preventive strategy for early detection and endoscopic removal of metachronous adenoma in patients with colorectal cancer (CRC). Here, we retrospectively explored the associated factors of metachronous adenoma in these patients. Methods: This study recruited 551 patients with stage I and II CRC who underwent radical surgery between January 1, 2012 and July 1, 2017 with postoperative colonoscopic surveillance. Data on clinicopathological characteristics and surveillance colonoscopies were obtained from medical records. Univariate analysis by Kaplan-Meier method and multivariate analysis by Cox proportional hazards model were used to identify the factors associated with metachronous adenoma. Results: Metachronous adenoma was detected in 110 (20.0%) patients. In these patients, 94.5% (104/110) had metachronous adenoma within 3 years postoperatively. Age, synchronous adenoma, hypertension, tumor stage, and surgical resection were correlated with metachronous adenoma in patients with stage I-II CRC after radical resection (log rank test, P<0.05). Multivariate analyses showed that synchronous adenoma (HR=2.515, 95% CI: 1.691-3.742, P<0.01); stage II (HR=2.066, 95% CI: 1.329-3.210, P<0.01); and left-side colorectal resection (HR=2.207, 95% CI: 1.292-3.772, P<0.01) were independent risk factors. Conclusions: Synchronous adenoma, left-side colorectal resection, and stage II cancer are independent risk factors of metachronous adenoma in patients with previous stage I and II CRC. In patients with risk factors, an enhanced colonoscopic strategy might be needed for early detection and timely endoscopic removal of metachronous adenoma.