Cold snare polypectomy and underwater endoscopic mucosal resection for superficial nonampullary duodenal epithelial tumors

Although the diagnostic and therapeutic opportunities for superficial nonampullary duodenal epithelial tumors (SNADETs) have been increasing, the natural history and treatment outcomes remain unclear. Due to the anatomical characteristics of the duodenum, clinicians should be more sensitive to the occurrence of complications for tumors in the duodenum compared to other gastrointestinal tumors. Recently, with the expectation of minimally invasive treatment, cold snare polypectomy (CSP) and underwater endoscopic mucosal resection (UEMR) have been accepted as simple and safe endoscopic treatments for SNADETs. In our institution, CSP achieved good treatment outcomes: a median procedure time of 3 (range, 1-23) min, an en bloc resection rate of 96.9%, an R0 resection rate of 50.0%, and a low incidence of adverse events (no delayed bleeding and no intra- and postoperative perforation). Moreover, UEMR also achieved good treatment outcomes: a median procedure time of 5 (range, 1-104) min, an en bloc resection rate of 82.9%, an R0 resection rate of 52.0%, and a low incidence of adverse events (delayed bleeding occurred in 2.6% of cases, and there were no incidences of no intra- and postoperative perforation). Residual recurrences occurred in two lesions (4.1%) that were treated with CSP and three lesions (4.8%) that were treated with UEMR, but these recurrences could be treated by re-endoscopic resection. Although there are limited data on these treatments for SNADETs, some previous reports and our data suggest that CSP could be indicated for adenomas sized 10 mm or less and that UEMR could be indicated for adenomas sized 10-20 mm and for intramucosal carcinomas. However, at present, the number of cases evaluated is still insufficient, and further studies are needed to evaluate long-term outcomes with enough cases.