ENDOSCOPIC MUCOSAL RESECTION OF NON-AMPULLARY DUODENAL ADENOMAS: RESULTS ON SAFETY AND RISK FACTORS FOR RECURRENCE FROM A LARGE TERITARY CENTER

Introduction
Duodenal adenomas have low incidence rates (<5%), but this is rising with increased use of endoscopy. Management and outcomes of duodenal adenomas are predominantly per case reports and series, but with malignant risk up to 85% when untreated and postresection recurrence rates up to 39%, there is a need for evidence-based management approaches. This study examines the safety and recurrence rates of endoscopic mucosal resection (EMR) of duodenal polyps.

Methods
Patients with non-ampullary duodenal adenomas who were candidates for EMR were identified using a procedure database from 2013 to 2023 at a single tertiary referral center. Demographics, polyp characteristics, and procedure-related variables were retrospectively collected via chart review.

Results
131 patients underwent 171 endoscopies for duodenal EMR. 15 patients had repeat duodenal EMRs with mean of 3 procedures (range 2-10). 74/131 (56.4%) were females and average age of 62 (Table 1). 17 patients (13.0%) had genetic predisposition to polyposis (i.e., familial adenomatous polyposis). Average polyp size was 20.8mm (range 3-50mm) and majority located distal to the ampulla (62.0%). Majority (169/171; 98.8%) were submucosally lifted prior to resection and removed via hot snare (142/171; 83.0%) (Table 2). 97.1% had complete resection and 49.1% were resected en-bloc. Most resections had hemostasis technique performed (155/171; 90.6%), mainly via clips. Adverse events occurred after 6 resections (3.5%), all were post procedural bleeding, and 5 treated endoscopically. Recurrence/residual neoplasia was present in 39/127 (30.7%) resection sites that had follow-up, with piecemeal EMR having higher recurrence rate vs en-bloc (45.3% vs 15.9%, p=0.0003). After excluding patients with genetic predisposition, en-bloc resection was associated with significantly lower recurrence rates (12.7% vs. 31.4%, p=0.027), whereas tubulovillous adenoma on pathology was associated with higher recurrence rates (22.7% vs. 4%, p=0.005). No other factors were associated with recurrence, including lesion size, Paris classification or use of adjunctive ablative therapy.

Conclusion
To our knowledge, this is one of the biggest US-based cohort studies evaluating EMR outcomes for large non-ampullary duodenal adenomas. Our results demonstrate that non-ampullary duodenal EMR is safe and effective. The 3.5% risk of delayed bleeding reported in our data as the only adverse event is lower than that in the published literature, which may be due to use of hemostasis techniques in most cases. Tubulovillous histology was found to be a risk factor for recurrence for non-ampullary duodenal adenomas. While EMR techniques may vary, our data support routine use of hemostasis techniques and consider more vigilant surveillance intervals in those with advanced histology. Larger scale studies are warranted to validate these results.