Risk of gastric epithelial neoplasms in autoimmune gastritis compared with severe Helicobacter pylori–associated gastritis: a matched cohort study in Japan

Abstract Background The association between autoimmune gastritis (AIG) and gastric epithelial neoplasms remains controversial, particularly in relation to Helicobacter pylori infection status. This study compared the risk of gastric epithelial neoplasms among individuals with AIG, severe H. pylori -associated gastritis (HPG), and H. pylori –uninfected normal stomach. Methods A total of 8,104 individuals who underwent screening upper gastrointestinal endoscopy and serum H. pylori antibody testing between 2014 and 2025 were enrolled. Fifty-six H. pylori -negative individuals were diagnosed with AIG based on endoscopic and serological criteria. Two control groups were established: severe HPG ( n = 723) and H. pylori -uninfected normal stomach ( n = 3,143). Matched cohort analyses using 1:5 greedy matching on sex, age, and follow-up duration were performed. The association between AIG and gastric epithelial neoplasms was evaluated using conditional logistic regression stratified by matched set. Results Over mean follow-ups of 1,935 and 1,494 days, gastric epithelial neoplasms developed in 8.9% (5 of 56 individuals; 2 cancers and 3 adenomas) of AIG group and 5.8% (42 of 723 individuals; 34 cancers and 8 adenomas) of severe HPG group, respectively. After matching, the incidence of gastric epithelial neoplasms was significantly higher in AIG than in severe HPG (odds ratio [OR] 4.58, p = 0.017). Compared with H. pylori -uninfected normal stomach, AIG also demonstrated a markedly increased risk (OR 33.63, p = 0.0003). Conclusions AIG without current H. pylori infection is associated with a significantly increased risk of gastric epithelial neoplasia compared with H. pylori -associated atrophic gastritis. AIG should be recognized as a high-risk condition requiring careful upper gastrointestinal surveillance.