Beyond Incidence and Mortality: Socioeconomic Mediation of Gastric Cancer Disparities in the United States, 1990–2021

<i>Background:</i> Gastric cancer (GC) remains a major global health burden, yet US trends often obscure disparities hidden within national averages. Although incidence and mortality have declined overall, profound geographic, racial, and socioeconomic differences persist. Few studies have systematically examined how demographic composition and social determinants jointly shape GC burden across states. <i>Methods:</i> We analyzed Global Burden of Disease 2021 estimates for GC incidence, mortality, and disability-adjusted life years (DALYs) from 1990 to 2021 across 50 US states and the District of Columbia. Outcomes were stratified by age, sex, race/ethnicity, and sociodemographic index. Multivariable and mediation models assessed how income and education modified racial and ethnic disparities. <i>Results:</i> While national GC rates declined over three decades, the burden remained concentrated in states with large immigrant and low-income populations, including Hawaii, the District of Columbia, Mississippi, and New Mexico. States with higher Asian populations exhibited roughly fourfold greater incidence than those with larger Hispanic populations. Income and education together mediated 22%-31% of racial and ethnic disparities, demonstrating that socioeconomic position-not race alone-drives much of the observed heterogeneity. <i>Conclusions:</i> This state-level sociodemographic analysis reveals the structural underpinnings of US GC inequities within a broader global context of uneven early-life risk and population diversity. By linking racial composition, income, and education to disease burden, it identifies modifiable pathways for prevention and policy action. Viewed as a case study for migrant-receiving countries, these findings underscore the importance of equity-informed strategies-such as <i>Helicobacter pylori</i> screening, nutrition interventions, and targeted resource allocation-to address persistent GC disparities globally.