Clinical Outcomes of Endoscopic Resection for Gastric and Duodenal Neuroendocrine Tumors

Background/Aims: Gastric and duodenal neuroendocrine tumors (NETs) are rare but have been increasingly detected due to the increased use of upper endoscopy in South Korea. Of these malignancies, small, superficial upper gastrointestinal NETs can be treated with endoscopic resection (ER). This study aimed to evaluate the clinicopathological characteristics of a single-center cohort with gastric NETs (G-NETs) and duodenal NETs (D-NETs) and their long-term outcomes following ER. Methods: We retrospectively analyzed the data of a prospectively assessed cohort of patients with G-NETs and D-NETs treated with ER between January 2006 and December 2023. A total of 144 patients were included, including 131 cases of G-NETs and 56 cases of D-NETs. We evaluated the clinicopathological characteristics of these patients and assessed their long-term outcomes following ER. Results: Among the patients with G-NETs, the proportions of type I, II, and III G-NETs were 47.3%, 0.8%, and 29.0%, respectively. The median follow-up period was 54.0 months (range, 0 to 161 months). The curative resection rates were 81.0% for type I/II and 60.5% for type III G-NETs (p=0.025). Ten patients underwent additional surgery after ER; however, no lymph node metastases were observed. The disease-specific survival rate was 100%. Ten cases experienced intragastric recurrence, and all were managed with repeat ER. Among the 56 patients with D-NETs, the curative resection rate was 41.1%. Two patients recurred, one with intraduodenal recurrence and the other with liver metastasis. No disease-specific deaths were reported. Conclusions: ER is a safe and effective method for treating gastric NETs, including type III, and for grade 1 D-NETs and results in favorable long-term outcomes.