Background/aims: Although there are guidelines for colonoscopic surveillance after colorectal cancer (CRC) surgery, the data evaluating the effectiveness of these guidelines are limited. We determined the risk factors for metachronous neoplasia (MN) by performing annual colonoscopy examinations after curative resection.
Methods: We performed annual colonoscopic surveillance on stage I-III CRC patients after curative resection. We stratified the patients based on the advanced neoplasia risk during the surveillance.
Results: Advanced MN detected was in 59 (13.1%) of 451 patients. Overall, the cumulative incidence of advanced MN was 17.3% at 5 years. By the multivariate analysis, the risk factors for advanced MN were male gender, age >65, left-sided index cancer and being in the high-risk group. The cumulative incidence of advanced MN was 38.9% at 5 years in the high-risk group. Among the patients who had advanced MN, secondary advanced MN was detected in 13 patients (22.0%) with a subsequent colonoscopy. The 2-year cumulative incidence of secondary advanced MN was 16.9%. Four (0.88%) patients had metachronous CRC during the surveillance and the interval from the index CRC was a median of 58.5 months.
Conclusions: Although the current follow-up guidelines for colonoscopic surveillance after CRC are well established, the high-risk group calls for more meticulous follow-up, which should be continued for a sufficient time.