Characteristics and Incidence of Gastric Cancer Among Patients with Autoimmune and Non-autoimmune Atrophic Gastritis in a U.S. Population.

BACKGROUND

Autoimmune gastritis (AIG) is a risk factor for gastric neuroendocrine tumor (NET). We compared risk factors between AIG cases, non-autoimmune atrophic gastritis (NAIG) cases, and normal controls and determined the incidence of gastric malignancy, including adenocarcinoma and NET.

METHODS

We included patients who underwent endoscopy with gastric biopsy between 3/2006 and 9/2021 in Harris Health (Houston, Texas). We identified AIG cases, NAIG cases (gastric atrophy or intestinal metaplasia [GIM] without autoimmune features), and normal controls (without AIG, NIAG, and GIM). A GI pathologist confirmed AIG diagnosis on histopathology report or slide. We determined risk factors of AIG compared to NAIG cases and normal controls and compared gastric malignancy incidence.

RESULTS

We included 158 AIG cases, 445 NAIG cases, and 2389 controls. Compared to NAIG cases, male sex (adjusted odds ratio [OR] 0.33; 95% confidence interval [CI] 0.21-0.51), current tobacco use (adj OR 0.29; 95% CI 0.14-0.61), and H. pylori (adj OR 0.35; 95% CI 0.24-0.53) were inversely associated with AIG. Anti-parietal cell antibody positivity and elevated gastrin level were associated with AIG. Compared to normal controls, Hispanic and Asian race/ethnicity and age > 40 were associated with AIG. The risk of gastric malignancy, particularly NET, was 2.7-fold higher with AIG compared to NAIG.

CONCLUSIONS

We found several risk factors (age, non-white race, female sex, non-tobacco user, lack of H. pylori) to be associated with AIG. The risk of gastric malignancy was elevated in AIG compared to NAIG which already is a precancerous condition. Early identification of AIG is important for cancer screening.