RT Book, Section A1 Ursem, Carling A1 McQuaid, Kenneth R. A2 Papadakis, Maxine A. A2 McPhee, Stephen J. A2 Rabow, Michael W. A2 McQuaid, Kenneth R. SR Print(0) ID 1184389723 T1 Gastric Neuroendocrine Tumors T2 Current Medical Diagnosis & Treatment 2022 YR 2022 FD 2022 PB McGraw-Hill Education PP New York, NY SN 9781264269389 LK accessmedicine.mhmedical.com/content.aspx?aid=1184389723 RD 2024/03/28 AB Gastric NETs make up less than 1% of gastric neoplasms. They may occur sporadically or secondary to chronic hypergastrinemia that results in hyperplasia and transformation of enterochromaffin cells in the gastric fundus. The majority of NETs are caused by hypergastrinemia and occur in association with either pernicious anemia (75%) (type 1) or Zollinger-Ellison syndrome (5%) (type 2). Type 1 tumors are associated with chronic atrophic gastritis, gastric achlorhydria, and secondary hypergastrinemia. Initial diagnostic workup includes serum gastrin level, upper endoscopy, and EUS. Gastrin level should be obtained 1 week after the patient has stopped taking protein pump inhibitors. For low-grade tumors (Ki-67 less than 3% or less than 2 mitoses/10 high-power fields [HPF]), somatostatin receptor–based imaging (somatostatin receptor scintigraphy or gallium-68 dotatate PET/CT) should be performed. For high-grade tumors (Ki-67 greater than 20% or greater than 20 mitoses/10 HPF), FDG-PET/CT is preferred to evaluate the extent of disease.