Positive Margins and Lymphovascular Invasion Represent Risk Factors for Remnant Tumor or Late Recurrence in Endoscopic or Local Resection of Duodenal Neuroendocrine Tumors

INTRODUCTION: Duodenal neuroendocrine tumors (DNETs) are rare neoplasms with malignant potential, and the optimal strategy between endoscopic resection (ER) and surgical resection (SR) remains debated. This study evaluated the clinical outcomes of ER and SR in patients with DNETs at a single tertiary center. METHODS: We retrospectively reviewed patients diagnosed with DNETs at Seoul St. Mary's Hospital between 2009 and 2025. The clinical features, treatment modalities, pathology, complications, and long-term outcomes were analyzed. Median follow-up was 4.76 years (0.03-13.70). RESULTS: Sixty-five patients were included (mean age, 62.9 years; 31 men). Fifty patients underwent ER (26 EMR, 9 EMR-L, 11 EMR-P, 1 ESD, 2 ampullectomy, and 1 removal with hot biopsy), while 15 underwent SR (10 wedge resections and 5 pancreatoduodenectomy/Whipple). The en bloc resection rate for ER was 93.9% (46/49), with a histopathologically curative resection rate of 69.4%. Fourteen ER patients had positive margins; one underwent additional surgery with a confirmed residual tumor, but the others showed no recurrence during a median follow-up of 6.8 years. Perforation occurred in three ER cases (6%), all of whom were successfully treated. Among the wedge resections, R1 resection occurred in 3/10 cases. One patient developed lymph node recurrence 12 years after wedge resection, whereas the others remained disease-free. Overall, recurrence was rare in both groups. CONCLUSION: ER and surgical local resection are effective, minimally invasive treatments for small DNETs, with high resection rates and acceptable safety. However, positive margins and lymphovascular invasion are risk factors for remnant tumors or late recurrence, underscoring the importance of long-term surveillance in high-risk patients.