Underwater endoscopic mucosal resection versus endoscopic submucosal dissection for 20-30 mm colorectal polyps.

BACKGROUND AND AIM: Endoscopic submucosal dissection (ESD) for large polyps provides a high en bloc resection rate, accurate pathological diagnosis, and low recurrence rate. However, ESD requires advanced techniques, and underwater endoscopic mucosal resection (UEMR) is an alternative. We investigated the efficacy and safety of UEMR for 20-30 mm colorectal lesions compared with ESD. METHODS: We retrospectively evaluated systematically collected data of patients who underwent UEMR or ESD for 20-30 mm sessile colorectal lesions. Outcome measures were the incidence of local recurrence, procedure time, en bloc resection rate, and incidence of adverse events. We performed propensity score matching and inverse probability weighting adjustment to control for possible confounders. RESULTS: We evaluated 125 patients undergoing UEMR and 306 patients undergoing ESD. Using propensity score matching, we analyzed 74 lesions in each group. UEMR had a shorter procedure time than ESD [6.7 min (95% confidence interval (CI), 5.3-8.1 min) vs 64.8 min (95% CI, 57.4-72.2 min), respectively]. Although the en bloc resection rate with UEMR was inferior to ESD [61% (95% CI, 49-72%) vs 99% (95% CI, 93-100%), respectively], there was no significant difference in the local recurrence rate between the procedures [0% (95% CI, 0-4.0%) in each group]. Inverse probability weighting adjustment revealed that neither ESD nor UEMR had a significant association with local recurrence. CONCLUSIONS: Underwater endoscopic mucosal resection for 20-30  mm colorectal lesions was comparable with ESD regarding long-term outcomes, with a shorter procedure time, despite the lower en bloc resection rate.