In this trial performed post-standardization of the endoscopic submucosal dissection (ESD) technique throughout Japan, a higher curability, shorter procedure time, and lower risk of complications were evident compared to those documented previously. Since target lesions of ESD are more advanced compared to those of endoscopic mucosal resection, ESD can serve as a first-line treatment for large colorectal lesions with acceptable risk and procedure time.

• In this multicenter, large-scale, prospective cohort trial of ESD performed at 20 institutions in Japan, ESD done for 1,883 patients (1,965 lesions) were analyzed.

• Mean procedure time was 80.6 min.

• En bloc and curative resections were accomplished in 1,759 (97.0%) and 1,640 (90.4%) lesions, respectively, in epithelial lesions ≥20 mm.

• In 51 (2.6%) and 12 (0.6%) lesions, intra- and postprocedural perforations developed respectively.

• Nine patients (0.5%) required emergency surgery for adverse events.