Underwater Endoscopic Mucosal Resection Versus Conventional Endoscopic Mucosal Resection for Superficial Non-ampullary Duodenal Epithelial Tumors ≤20 mm

Background: Underwater endoscopic mucosal resection (UEMR) is increasingly applied in the treatment of superficial non-ampullary duodenal epithelial tumors (SNADETs). This meta-analysis aimed to assess the efficacy and safety of UEMR for SNADETs ≤20 mm in comparison with conventional endoscopic mucosal resection (CEMR). Methods: The following electronic databases were searched from 2012 until November 20, 2021: PubMed, Embase, Scopus, Web of Science databases, and Cochrane Library. The primary outcomes were the rates of en bloc resection and complete (R0) resection, and the secondary outcomes were procedure time, adverse events (delayed bleeding and delayed perforation), and recurrence rate. Results: A total of 6 studies with 679 lesions (331 underwent UEMR and 348 CEMR) were included in this study. The pooled analysis showed that UMER achieves a similar en bloc resection rate (87.6 vs. 89.9%; odds ratio [OR], 1.29; 95% confidence interval [CI], 0.45 to 3.73; P =0.64; I 2 =74%), a similar R0 resection rate (67.3 vs. 73.6%; OR, 1.11; 95% CI, 0.55 to 2.23; P =0.78; I 2 =59%), a shorter procedure time (min) (mean difference [MD], −4.05, 95% CI: −6.40 to −1.71; P =0.0007; I 2 =70%) compared with CEMR. There were no significant differences in the rates of delayed bleeding, delayed perforation, and recurrence (2.4 vs. 1.7%, 0 vs. 0.6%, 2.2 vs. 4.4%, respectively). Conclusion: This meta-analysis demonstrated that UEMR appears to be an effective and safe alternative to CEMR for SNADETs ≤20 mm.