Utility of underwater EMR for nonpolypoid superficial nonampullary duodenal epithelial tumors ≤20 mm.

Abstract Background and Aims The application of underwater endoscopic mucosal resection (UEMR) for nonpolypoid superficial nonampullary duodenal epithelial tumors (SNADET) has not been comprehensively assessed. Therefore, the current study aimed to validate the efficacy of UEMR versus conventional endoscopic mucosal resection (EMR) and cap-assisted endoscopic mucosal resection (EMRC) for SNADET measuring ≤20 mm. Methods We retrospectively analyzed patients with sporadic nonpolypoid SNADET measuring ≤20 mm. They underwent EMR, EMRC, or UEMR at Chiba University Hospital between May 2004 and October 2020 (EMR 21 patients 23 SNADET, UEMR 60 patients 61 SNADET, EMRC 45 patients 48 SNADET). A weighted logistic regression analysis was performed to analyze outcomes. Univariate and multivariate logistic regression models were used to identify the predictors of RX/1 and piecemeal resection. The recurrence rate of lesions observed ≥12 months after resection was assessed. Results Both UEMR and EMRC had a significantly higher R0 resection rate than EMR. UEMR had significantly lower multiple resection and post-bleeding rates than EMR. Only one (2.1%) patient who underwent EMRC experienced intraoperative and postoperative perforation. EMR was involved in RX/1 and piecemeal resection. The recurrence rates of EMR, UEMR, and EMRC were 4.3%, 2.0%, and 6.3%, respectively. Conclusions UEMR had significantly higher R0 resection and lower postbleeding rates than EMR. Moreover, it was safer than EMRC and was associated with a lower incidence of recurrences. The significant results of the retrospective analysis suggest a randomized controlled study with adequate numbers need to be conducted to confirm the superior efficacy of UEMR before it is recommended for primary treatment option for SNADET measuring ≤20 mm.