van de Ven SEM, Backes Y, Hilbink M, et al. - Medical records of individuals with T1 colorectal cancer (CRC) diagnosed between 2000 and 2014 in 15 hospitals in the Netherlands were analyzed in order to recognize the adverse event (AE) rate following endoscopic resection (ER) of T1 CRCs and to determine the risk factors related to these AEs. In 59 of 1,069 people, endoscopic AEs transpired, of which 37.3% and 59.3%, and 3.4% were classified as mild, moderate, and severe, respectively. Postprocedural bleeding (n = 40), perforation (n = 13), and postpolypectomy electrocoagulation syndrome (n = 6) were the AEs. No fatal AEs were seen. In summary, AE rates of ER of T1 CRC are similar to reported AE rates for adenomas in this large multicenter retrospective cohort study. For AEs, larger tumor size and age > 70 years are independent predictors. Thus, this study implies that endoscopic treatment of T1 CRCs is not related to an extended periprocedural AE risk.