'Underwater endoscopic mucosal resection with submucosal injection and marking' for superficial non-ampullary duodenal epithelial tumors to achieve R0 resection: a single-center case series.

OBJECTIVES:To describe an endoscopic technique named 'underwater endoscopic mucosal resection (UEMR) with submucosal injection and marking (UEMR-SIM)' and to evaluate the therapeutic characteristics of superficial non-ampullary duodenal epithelial tumors (SNADETs) < 20 mm vis-a-vis classical EMR (CEMR) and UEMR techniques. MATERIALS AND METHODS:This retrospective study included 103 consecutive SNADET patients (103 lesions) who underwent CEMR, UEMR, or UEMR-SIM. The UEMR-SIM procedure included (1) marking and submucosal injection, (2) filling of the duodenal lumen with 0.9% saline, (3) snaring of the lesion, and (4) electrosurgical removal. The procedural outcomes were compared between the UEMR-SIM and other-procedure groups. RESULTS:The en bloc resection rate was significantly higher in the UEMR-SIM group (100%) than in the CEMR group (76.8%) (p = 0.015) but was not statistically different between the UEMR-SIM and UEMR groups (88.0%) (p = 0.236). The R0 resection rate was significantly higher in the UEMR-SIM group (90.9%) than in the UEMR group (48.0%) (p = 0.001) but was not statistically different between the UEMR-SIM and CEMR groups (76.8%) (p = 0.209). CONCLUSIONS:Our study indicates that the proposed method, UEMR-SIM for SNADETs, is feasible to achieve a high R0 resection rate and a potentially low local recurrence rate.