LAUSR

BACKGROUND AND AIMS High-quality data regarding the effect of Helicobacter pylori (H. pylori) eradication on the risk of noncardia gastric adenocarcinoma (NCGA) remain limited in the United States (U.S). We investigated the incidence of NCGA after H. pylori eradication therapy in a large, community-based U.S. POPULATION METHODS We performed a retrospective cohort study of Kaiser Permanente Northern California (KPNC) members who underwent testing and/or treatment for H. pylori between 1997-2015 and were followed through 12/31/2018. The risk of NCGA was evaluated using Fine-Gray subdistribution hazard model and standardized incidence ratios (SIRs). RESULTS Among 716,567 individuals with a history of H. pylori testing and/or treatment, the adjusted subdistribution hazard ratios (sHRs) and 95% CIs of NCGA for H. pylori positive/untreated and H. pylori positive/treated individuals were 6.07 (4.20-8.76) and 2.68 (1.86-3.86), respectively, compared with H. pylori negative individuals. When compared directly with H. pylori positive/untreated individuals, sHRs for NCGA in H. pylori positive/treated were 0.95 (0.47-1.91) at <8 years and 0.37 (0.14-0.97) ≥ 8 years of follow-up. Compared with KPNC general population, SIRs (95% CI) of NCGA steadily decreased after H. pylori treatment: 2.00 (1.79-2.24) ≥1 year, 1.01 (0.85-1.19) ≥4 years, 0.68 (0.54-0.85) ≥7 years, and 0.51 (0.38-0.68) ≥10 years. CONCLUSION In a large, diverse, community-based population, H. pylori eradication therapy was associated with a significantly reduced incidence of NCGA after 8 years compared with no treatment. The risk among treated individuals became lower than the general population after 7-10 years of follow-up. The findings support the potential for substantial gastric cancer prevention in the U.S. through H. pylori eradication.