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

The application of underwater EMR (UEMR) for nonpolypoid superficial nonampullary duodenal epithelial tumors (SNADETs) has not been comprehensively assessed. Therefore, the current study aimed to validate the efficacy of UEMR versus conventional EMR and cap-assisted EMR (EMRC) for SNADETs measuring ≤20 mm.We retrospectively analyzed patients with sporadic nonpolypoid SNADETs measuring ≤20 mm undergoing EMR, EMRC, or UEMR at Chiba University Hospital between May 2004 and October 2020 (EMR, 21 patients and 23 SNADETs; UEMR, 60 patients and 61 SNADETs; EMRC, 45 patients and 48 SNADETs). 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.Both UEMR and EMRC had a significantly higher R0 resection rate than EMR. UEMR had significantly lower multiple resection and postbleeding rates than EMR. Only 1 patient (2.1%) 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.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 needs to be conducted to confirm the superior efficacy of UEMR before it is recommended for primary treatment option for SNADETs measuring ≤20 mm.