Neuroendocrine tumors of the stomach and duodenum: evolving classification, endoscopic management, and surveillance

Gastric and duodenal neuroendocrine tumors are increasingly encountered in gastroenterology practice, often as incidental findings during upper endoscopy or cross-sectional imaging. This review summarizes recent advances in epidemiology, classification, diagnostic evaluation, endoscopic management, surgical decision-making, and surveillance for these tumors.

Contemporary epidemiologic data show a rising incidence of gastroenteropancreatic neuroendocrine neoplasms, likely reflecting increased endoscopic detection, improved imaging, and greater diagnostic recognition. Modern classification emphasizes anatomic site, differentiation, grade, functional status, and subtype-specific biology. For gastric neuroendocrine tumors, management differs substantially among type 1, type 2, type 3, and emerging proton pump inhibitor-associated tumors. Type 1 tumors are usually indolent and may be managed with surveillance or endoscopic resection, whereas type 3 tumors require careful staging because of higher metastatic potential. For duodenal neuroendocrine tumors, tumor location, particularly ampullary or periampullary involvement, strongly influences staging, resection strategy, and surveillance. Endoscopic resection is increasingly used for selected low-risk lesions, including small type 3 gastric neuroendocrine tumors and nonampullary duodenal neuroendocrine tumors, although prospective evidence remains limited.

Gastric and duodenal neuroendocrine tumors require individualized, risk-adapted management based on site, subtype, size, grade, invasion depth, lymphovascular invasion, nodal status, metastatic disease, and functional context. Endoscopy remains central to diagnosis and treatment, while EUS, cross-sectional imaging, and somatostatin receptor imaging should be used selectively when results will alter management. Multidisciplinary decision-making is essential for higher risk lesions, borderline cases, and patients being considered for organ-preserving therapy.