Ambient Air Pollution and Gastric Cancer Incidence: A Multinational Ecological Analysis (1990-2020)

While ambient air pollution constitutes a major global health risk, its long-term association with gastric cancer burden at a global scale, especially its impact on vulnerable populations, remains poorly characterized. We examined the association between long-term exposure to ambient air pollution and gastric cancer incidence.

In this ecological study, we analyzed data from 204 countries (1990-2020) from the Global Burden of Disease 2021 study. We examined the association between age-standardized incidence rates of gastric cancer and long-term exposure to fine particulate matter (PM_2.5), nitrogen dioxide (NO₂), and ozone (O₃). We used adjusted negative binomial fixed-effects panel regression, natural cubic splines for nonlinearity, stratified analyses by sex, age, and sociodemographic index (SDI), and lag models.

Significant positive associations were found. Each one-unit increase in PM_2.5, NO₂, and O₃ was associated with 0.3% (95% CI: 0.1-0.5%), 1.8% (1.2-2.4%), and 0.6% (0.3-0.9%) increases in overall incidence, respectively, at the population level. The exposure‒response relationships were nonlinear, with critical lag windows of 3-4 years for PM_2.5 and 3 years for O₃. Stratified analyses revealed greater male susceptibility to PM_2.5, whereas females were more vulnerable to NO₂ and O₃. High-middle-SDI regions had the highest PM_2.5 risk, whereas low-middle-SDI regions were most affected by NO₂ and O₃. Adults aged ≥70 years face the highest risk, with females showing elevated susceptibility after age 60.

These ecological findings highlight the importance of considering air pollution in gastric cancer prevention frameworks, although the results must be validated by individual-level studies across diverse settings before causal inferences can be drawn.