INCIDENCE AND RISK OF GASTRIC NEUROENDOCRINE TUMORS (gNET) AND ADENOCARCINOMA IN PATIENTS WITH ATROPHIC GASTRITIS/PERNICIOUS ANEMIA.

Background: Atrophic gastritis, particularly in the context of autoimmune mechanisms or chronic Helicobacter pylori infection, is a recognized precursor to gastric neoplasia. However, surveillance strategies remain inconsistent. This study aimed to determine the cumulative incidence and risk factors for gastric neuroendocrine tumor and adenocarcinoma in a large U.S. based cohort of patients with atrophic gastritis.

Methods: We conducted a retrospective cohort study of 224 patients diagnosed with atrophic gastritis at the Mayo Clinic Enterprise between 2010 and 2023. Patients with prevalent gastric neuroendocrine tumor (n=25) or adenocarcinoma (n=7) were excluded from respective survival analyses. Kaplan-Meier methods estimated 5- and 10-year cumulative incidence, and univariable Cox regression identified risk factors for neoplastic progression.

Results: Among 199 patients at risk for gastric neuroendocrine tumor, the 5- and 10-year cumulative incidence was 6% and 18%, respectively. Hypergastrinemia and alcohol use disorder were associated with increased gastric neuroendocrine tumor risk. For the 217 patients at risk for adenocarcinoma, the 5- and 10-year cumulative incidence was 3% and 9%, respectively. Severe dysplasia and a history of peptic ulcer disease were the strongest predictors of adenocarcinoma. Histologic severity alone was not a reliable predictor of neoplastic progression.

Conclusions: Patients with atrophic gastritis face significantly elevated risks of both gastric neuroendocrine tumor and adenocarcinoma compared to the general population. Risk stratification based on clinical and biochemical factors-such as hypergastrinemia, alcohol use, and dysplasia-may better inform surveillance strategies than histology alone. These findings support more personalized endoscopic surveillance protocols in high-risk atrophic gastritis populations.