Population-Level Trends in Gastric Cancer Mortality and Incidence After Expansion of Japanese National Health Insurance Coverage for Helicobacter pylori Eradication: A Descriptive Time-Trend Study.

BACKGROUND: In February 2013, Japanese national health insurance coverage for Helicobacter pylori eradication was expanded to patients with H. pylori-positive, endoscopically diagnosed chronic gastritis. This policy broadened access to eradication treatment, but its relationship with subsequent population-level gastric cancer trends requires cautious interpretation. AIM: To describe national trends in gastric cancer mortality and incidence before and after the 2013 insurance expansion, with attention to age-specific patterns, endoscopic screening, treatment uptake, and alternative explanations. METHODS: We examined publicly available national mortality data from the Ministry of Health, Labour and Welfare and cancer incidence data from the National Cancer Center. Calendar-year trends in annual gastric cancer deaths, incident cases, and age-specific deaths were evaluated descriptively. The 2013 policy change was treated as a major contextual event rather than as a causal intervention with an internally estimated counterfactual. RESULTS: Annual gastric cancer deaths declined from 48,427 in 2013 to 37,394 in 2024, a 25.2% reduction in crude annual deaths. Incidence also decreased after a later peak, with available national incidence data showing fewer new cases by 2021. Age-specific analyses showed pronounced decreases in deaths among people younger than 80 years, whereas deaths among those aged 80 years or older continued to increase. CONCLUSION: After the 2013 expansion of insurance coverage for H. pylori eradication, gastric cancer mortality and incidence in Japan declined at the population level. These ecological trends are compatible with a contribution from increased eradication therapy and endoscopy-linked detection, but causality cannot be established from aggregate data alone. Age-standardized, claims-linked, stage-specific, and treatment-linked analyses are needed to quantify the independent policy effect.