Comparison of clinical outcomes between conventional and underwater endoscopic mucosal resection for duodenal neuroendocrine tumors.

Duodenal neuroendocrine tumors are relatively rare subepithelial tumors that arise from cells of the neuroendocrine system. Small duodenal neuroendocrine tumors can be treated endoscopically because of their low potential for metastasis. This study aimed to evaluate the clinical outcomes of conventional and underwater endoscopic mucosal resection for duodenal neuroendocrine tumors. Between March 2009 and March 2023, 15 patients with duodenal neuroendocrine tumors resected using conventional (n = 7) and underwater (n = 8) endoscopic mucosal resections were retrospectively enrolled. The median specimen size and median tumor size were 1.0 cm (interquartile range: 0.8-1.2 cm) and 0.6 cm (interquartile range: 0.4-0.6 cm), respectively. More than half of duodenal neuroendocrine tumors were located in the duodenal bulb (9/15, 60%). The en bloc and complete resection rates of both conventional and underwater endoscopic mucosal resections were 100%. Only one perforation event occurred in the conventional endoscopic mucosal resection group (14.3%). The patient with the perforation was treated with endoscopic clipping. The median follow-up period was 39.5 months (interquartile range: 19.5-57.3 months). There was no local recurrence or distant metastasis during the follow-up period. Underwater endoscopic mucosal resection is a safe and effective treatment option for small duodenal neuroendocrine tumors and is the preferred treatment option for flat-type duodenal neuroendocrine tumors.