Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 39-12: Gastric Neuroendocrine Tumors + Key Features Download Section PDF Listen +++ ++ Gastric neuroendocrine tumors (NETs) Rare Account for < 1% of gastric neoplasms Sporadic or secondary to chronic hypergastrinemia Gastric NETs secondary to chronic hypergastrinemia Type 1 gastric NETs occur in association with pernicious anemia (75% of cases) Type 2 gastric NETs occur with Zollinger-Ellison syndrome in multiple endocrine neoplasia type 1 (MEN 1) (5%) Tend to be multicentric, < 1 cm, with low potential for metastatic spread to the liver and thus unlikely to cause the carcinoid syndrome Type 3 gastric NETs arise sporadically, independent of gastrin production, and account for up to 20% of all gastric NETs + Clinical Findings Download Section PDF Listen +++ ++ Most asymptomatic, detected incidentally during endoscopy May ulcerate, causing occult GI bleeding and anemia Most sporadic gastric carcinoids are solitary, > 2 cm in size, and have a strong propensity for hepatic or pulmonary metastases + Diagnosis Download Section PDF Listen +++ ++ Initial diagnostic work-up includes serum gastrin level, upper endoscopy, and endoscopic ultrasound Gastrin level should be obtained after the patient has stopped taking proton pump inhibitors for 1 week For low-grade tumors (ki-67 < 3% or < 2 mitoses/10 HPF), somatostatin receptor-based imaging (somatostatin receptor scintigraphy or gallium-68 dotatate PET/CT) should be performed For high-grade tumors (ki-67 > 20% or > 20 mitoses/10 HPF), FDG-PET/CT is preferred to evaluate the extent of disease Serum vitamin B12 and intrinsic factor antibody levels should be obtained to exclude pernicious anemia In type 2 carcinoids associated with Zollinger-Ellison syndrome in MEN 1, chromosomal loss of 11q13 has been reported CT or MRI should be obtained to evaluate for metastatic disease Advanced, low-grade gastric NETs can be monitored with serial scans, if asymptomatic + Treatment Download Section PDF Listen +++ ++ Small lesions: endoscopic resection followed by periodic endoscopic surveillance or with observation Antrectomy reduces serum gastrin levels and may lead to regression of small tumors Octreotide therapy may be appropriate for patients with underlying gastrinoma and Zollinger-Ellison syndrome Patients with tumors > 2 cm in size should undergo endoscopic or surgical resection Localized sporadic NETs should be treated with radical gastrectomy and regional lymphadenectomy Sandostatin analogs may provide symptomatic relief for patients with functional gastric NETs Advanced high-grade gastric neuroendocrine carcinomas (NEC) are treated in a fashion similar to small cell lung cancers