Long-term exposure to fine particulate matter interacting with individual conditions increase breast cancer incidence: a large-scale Chinese cohort

Abstract

Background: Breast cancer is the most frequently diagnosed malignancy among women worldwide. This study aimed to investigate the impact of long-term fine particulate matter (PM2.5) exposure on breast cancer incidence in a cohort of 281,152 women from the China Kadoorie Biobank who were initially free of breast cancer. Results: PM2.5 concentrations were estimated using a high-resolution satellite-based model, and breast cancer cases were ascertained through national databases. Over a median follow-up of 11.12 years, 2393 new breast cancer cases were reported. Analyses using Cox proportional hazard and restricted cubic spline models demonstrated a non-linear association between PM2.5 exposure and breast cancer incidence, with a marked increase in risk observed once PM2.5surpassed 53.6 μg/m3. For every 10 μg/m3 increase in PM2.5, the hazard ratio for breast cancer incidence was 1.07 (95% confidence interval: 1.03–1.12). Furthermore, interactions were noted between PM2.5, physical activity, and life satisfaction, indicating that high pollution levels may diminish the protective benefits of exercise and positive psychological well-being. Conclusions: These findings highlight the need for stringent air pollution control measures and underscore the importance of integrated strategies that consider environmental, lifestyle, and psychological factors to reduce the burden of breast cancer.