Metachronous advanced neoplasia after submucosal invasive colorectal cancer resection

Little is known about the incidence of metachronous advanced neoplasia (AN) following resection of submucosal invasive colorectal cancer (SM-CRC). Here, we aimed to assess the occurrence of metachronous AN following SM-CRC resection. We retrospectively reviewed consecutive patients who underwent SM-CRC resection at an academic medical center between 2005 and 2013. Among 343 patients, 250 (72.9%) underwent surgical resection or endoscopic resection followed by surgical resection and 93 (27.1%) underwent only endoscopic resection. During a median follow-up period of 61.5 months, the overall incidence of metachronous AN was 7.6%, and the cumulative incidence at 5 years was 6.1%. The cumulative incidence was significantly higher in the endoscopic resection group than in surgical resection group, in patients with colonic disease than in those with rectal disease, and in patients with synchronous AN than in those without. Multivariate analysis revealed that synchronous AN was the only significant risk factor for metachronous AN (HR 4.35; 95% CI 1.88-10.1). These findings imply that depending on synchronous AN, a surveillance protocol following SM-CRC resection can be changed for better detection of metachronous AN.