Underwater Versus Conventional EMR for Superficial Nonampullary Duodenal Tumors ≤20 mm: A GRADE-Assessed Meta-Analysis.

Superficial nonampullary duodenal epithelial tumors (SNADETs) present significant challenges in endoscopic management due to their unique anatomic and histologic features, including thin muscularis propria, abundant vasculature, and Brunner glands. In this study, we aim to evaluate the efficacy and safety of underwater endoscopic mucosal resection (U-EMR) compared with conventional endoscopic mucosal resection (C-EMR) in treating SNADETs ≤20 mm. A systematic search was performed in PubMed, Web of Science, Scopus, and Embase from inception to June 1, 2025. Risk of bias assessment was performed by using the Newcastle-Ottawa scale for cohort studies. Data analysis was conducted using R version 4.2.2 (2022-10-31) and RStudio version 2022.07.2 (2009 to 2022, RStudio, Inc.). Outcomes included clinical success defined as no local recurrence detected on endoscopy after 3 to 6 months of follow-up. Findings from 11 studies involving 1465 patients indicate that U-EMR demonstrates a significantly higher clinical success rate (OR: 2.68, 95% CI: 1.58-4.55; P =0.0003, I2 =0%) and reduced procedure time (MD: -2.74, 95% CI: -5.05 to -0.44; P =0.0198, I2 =96.1%) compared with C-EMR, while showing no statistically significant differences in en bloc resection (OR: 1.42, 95% CI: 0.80-2.53; P =0.2297, I2 =60.2%), R0 resection rates (OR: 1.12, 95% CI: 0.69-1.83; P =0.6477, I2 =61.7%), delayed bleeding, intraoperative perforation, or recurrence rates between the 2 techniques. Despite the comparable safety profiles, the study suggests that U-EMR may offer practical advantages in clinical settings, particularly in terms of efficiency and procedural success; U-EMR is positioned as a potential approach for managing SNADETs.