Persistent Hypergastrinemia After Gastric NET Resection

Introduction to Gastric NET Management

The National Comprehensive Cancer Network recommends that patients with persistent hypergastrinemia after gastric NET resection undergo evaluation to determine the underlying cause, as this will guide management decisions 1

The National Comprehensive Cancer Network suggests stopping proton pump inhibitors for 1-2 weeks and remeasuring fasting gastrin to confirm that the elevation is not spurious 2
Measuring gastric pH can help distinguish between Type 1 and Type 2 gastric NETs, with a pH <2 indicating gastrinoma (Type 2) and a pH >4-5 indicating achlorhydria from atrophic gastritis (Type 1) 3

The National Comprehensive Cancer Network recommends obtaining multiphasic CT or MRI of the abdomen/pelvis to look for duodenal or pancreatic gastrinoma in patients with suspected Type 2 gastric NETs 2
Surveillance endoscopy every 6-12 months for the first 3 years, then annually, is recommended for patients with Type 1 gastric NETs 1

The National Comprehensive Cancer Network suggests that patients with Type 1 gastric NETs undergo surveillance endoscopy and consider antrectomy only if new lesions or increasing tumor burden develops 1
For patients with Type 2 gastric NETs, the National Comprehensive Cancer Network recommends locating and resecting the gastrinoma, usually duodenal or pancreatic, and using EUS for small duodenal gastrinomas 2

Gastric pH is the key discriminator between NET types, with pH >4-5 indicating Type 1 gastric NET (achlorhydria from atrophic gastritis) and pH <2 indicating Type 2 gastric NET (gastrinoma/Zollinger-Ellison syndrome) 4
Type 1 NETs account for 70-80% of all gastric NETs and are characterized by physiologic hypergastrinemia from parietal cell loss, with a low metastatic potential 4
The American Gastroenterological Association recommends that gastrin levels be interpreted with caution, as PPIs can cause false elevations, and that gastric pH be used to distinguish between Type 1 and Type 2 NETs 4

Ongoing endoscopic surveillance is mandatory after resection of gastric NETs, given the elevated risk of metachronous neoplasia, with surveillance intervals not well-defined for Type 1 gastric NETs but should continue indefinitely 4, 5
The National Comprehensive Cancer Network (NCCN) recommends surveillance every 6-12 months for up to 10 years for most gastric NETs 6

A gastric pH < 2 combined with a fasting gastrin level that is ≥10 times the upper limit of normal is diagnostic for gastrinoma, according to the NCCN guidelines. 7

Gastric pH measurement is indicated in patients in whom Zollinger‑Ellison syndrome is suspected (e.g., recurrent peptic ulcers, severe dyspepsia accompanied by diarrhea). This testing is performed after the acute bleeding episode has been managed. 7

Patients must discontinue proton‑pump inhibitor therapy for at least one week before gastric pH and gastrin testing to avoid false‑negative results. 7