Tip-In Underwater Endoscopic Mucosal Resection for Superficial Nonampullary Duodenal Epithelial Tumors ≤ 20 mm

Although underwater endoscopic mucosal resection (UEMR) is widely performed for superficial nonampullary duodenal epithelial tumors (SNADETs), its R0 resection rate remains unsatisfactory. Therefore, we developed a novel "tip-in UEMR" technique to ensure resection margins. This study aimed to evaluate the usefulness of tip-in UEMR for SNADETs ≤ 20 mm compared with conventional UEMR (C-UEMR).

This single-center retrospective study included SNADETs ≤ 20 mm treated with UEMR between January 2023 and October 2024. The primary endpoint was the R0 resection rate, and the secondary endpoints included the incidence of adverse events and local recurrence.

Of 147 SNADETs treated with UEMR, 128 were resected with C-UEMR and 19 with tip-in UEMR. Tip-in UEMR achieved a significantly higher R0 resection rate than C-UEMR (84.2% vs. 53.9%, p = 0.013) without an increase in adverse events. Local recurrence was observed in 3.9% of patients treated with C-UEMR, whereas no recurrence was observed in the tip-in UEMR group. Multivariate logistic regression analysis showed that tumor size < 10 mm (odds ratio [OR], 2.54; 95% confidence interval [CI], 1.24-5.22; p = 0.011) and tip-in UEMR (OR, 5.15; 95% CI, 1.33-20.0; p = 0.018) were independent factors associated with R0 resection. Notably, tip-in UEMR achieved a significantly higher R0 resection rate than C-UEMR for SNADETs sized 10-20 mm (p = 0.049).

Tip-in UEMR can be preferable for SNADETs ≤ 20 mm, particularly those sized 10-20 mm.