Trends and incidence of stomach cancer in middle-aged and elderly populations: a global burden of disease analysis.

Background: Stomach cancer remains a leading cause of cancer deaths in middle-aged and elderly populations. This study aimed to examine global trends in incidence among individuals aged 50-74 years and to explore disparities by age, sex, and region using Global Burden of Disease (GBD) data. Methods: Data on stomach cancer incidence were extracted from the GBD 2021 database. We analyzed incidence rates for individuals aged 50-74 years, stratified by age, sex, and geographic region. Trends from 1990 to 2021 were evaluated using the Estimated Annual Percentage Change (EAPC) based on log-linear regression models. Pearson correlation was used to examine associations between incidence trends and the Socio-Demographic Index (SDI). Data standardization was based on the GBD world standard population. Results: From 1990 to 2021, the number of stomach cancer cases among individuals aged 50-74 years increased by 17.32%, while the incidence rates declined from 80.67 to 44.18 per 100,000 (EAPC: -2.15). Males consistently exhibited higher incidence rates than females. The decline was less pronounced in older age groups, particularly those aged 65-74 years, where the number of cases continued to rise, reflecting population aging and cumulative risk exposure. High-SDI regions experienced the largest reductions (e.g., East Asia: EAPC -2.02), whereas progress was limited in low-SDI areas such as Southern and Eastern Sub-Saharan Africa. A strong negative correlation between SDI and incidence trends (ρ=-0.491) underscored the influence of socioeconomic development on disease reduction. Conclusions: This study reveals marked regional and demographic disparities in stomach cancer trends among aging populations. Socioeconomic development plays a central role in reducing incidence. To reduce global health inequities, efforts should prioritize equitable access to screening and treatment, culturally tailored prevention programs, and investment in healthcare infrastructure in low-SDI regions.