The thirty years trends of gastric cancer attributable to smoking in China and Japan: Demographic decomposition and age-period-cohort analysis.

BACKGROUND: China and Japan showed similar cultural backgrounds and lifestyles. This study aimed to assist China or Japan policymakers in allocating healthcare resources by examining secular trends in gastric cancer (GC) mortality attributable to smoking in China and Japan from 1992 to 2021. METHODS: Based on the Global Burden of Disease Study 2021, the mortality data for GC attributable to smoking were obtained to assess trends by the annual average percentage change and estimate age, period, and cohort effects by an age-period-cohort model. Smoking-attributable GC deaths were decomposed by decomposition analyses. RESULTS: From 1992 to 2021, age-standardized mortality rates of smoking-attributable GC decreased in China(48.00%) and Japan(73.48%). In China, smoking-attributable GC deaths for both sexes increased by over 26% mainly driven by population growth, while it decreased in Japan. The main reason for this decline was mortality rate(-120.10% in males and -106.31% in females). Notably, males had much more smoking-attributable GC deaths compared to females. In the two countries, age and cohort effects were similar, with a higher risk of smoking-attributable GC mortality rates observed among the elderly and earlier birth cohorts. However, the period effect decreased rapidly in Japan but increased nearly 1.4 times in China for both sexes during 1992-2001. Divergent trends in smoking-attributable GC mortality between China and Japan may be mainly explained by period effects. CONCLUSION: From 1992 to 2021,China showed higher risk than Japan in smoking-attributable GC mortality.Therefore, China should learn from Japan's strategies for GC screening and implement more effective tobacco control policies, particularly earlier birth cohorts and males.