Outcomes for Underwater Endoscopic Mucosal Resection and Endoscopic Submucosal Dissection of 21-30-mm Colorectal Polyps: A Feasible Study.

Background And Aims: This randomized controlled trial (RCT) was designed to evaluate the short-term outcomes of underwater endoscopic mucosal resection (UEMR) and endoscopic submucosal dissection (ESD) of 21-30 mm colonic polyps.

Method: We conducted a single-center RCT. Patients diagnosed with suspected colorectal intramucosal carcinoma (21-30 mm and adaptable for both UEMR and ESD) were randomly assigned to the UEMR and ESD groups at a 1:1 ratio. The primary endpoint was the R0 resection rate. We independently performed one-sample tests against the set threshold for each treatment. The significance level was set at p = 0.224.

Result: Eleven polyps each in the UEMR and ESD groups, respectively, were analyzed. The R0 resection rate (%) was 36 (95% confidence interval 11-69) and 100 (72-100) for UEMR and ESD, respectively, with a significant difference between the two groups (p = 0.002). The p-value against the set threshold for UEMR was 0.743, whereas that for ESD was < 0.001 (one-sample binomial test). The en bloc resection rates (%) were 82 (48-97) and 100 (72-100) for UEMR and ESD, respectively; however, no significant difference was observed (p = 0.167). The mean treatment time (min) was significantly shorter in the UEMR group (8 ± 6) than in the ESD group (48 ± 29) (p = 0.001).

Conclusion: ESD could achieve a high R0 resection rate, while the en bloc resection rate was comparable between the two treatment techniques with less burden on patients undergoing UEMR for 21-30-mm colorectal polyps.

Clinical Trial Registration: The study was registered at the Japan Registry of Clinical Trial as jRCT1030210015 and jRCT1030210177.