Ambient air pollution and mortality in older breast cancer patients
Menée à partir de données 2000-2016 des registres américains des cancers et de la base Medicare portant sur 593 333 patientes âgées de plus de 65 ans et atteintes d'un cancer du sein, cette étude de cohorte analyse l'association entre la pollution de l'air ambiant et la mortalité
Background: Although emerging studies link air pollution to mortality of breast cancer patients, large-scale evidence remains limited. We aim to evaluate associations between chronic exposures to fine particulate matter (PM2.5), ozone, and nitrogen dioxide (NO2) and mortality in a nationwide cohort of older breast cancer patients.
Methods: We constructed a cohort of breast cancer patients aged ≥65 years between 2000–2016 using SEER-Medicare database. High-resolution ambient concentrations of annual PM2.5, warm-season ozone, and annual NO2 were estimated using hybrid models and linked to patients’ residential ZIP codes as proxy exposures. Three-pollutant Cox model was fitted to estimate hazard ratio for mortality associated with each pollutant, adjusting for demographics, tumor characteristics, cancer treatments, comorbidities, lifestyle factors, meteorological variables, and neighborhood-level characteristics.
Results: Among 593,333 breast cancer patients, a 1-µg/m3 increase in annual PM2.5, 1-ppb increase in warm-season ozone, and 1-ppb increase in annual NO2 were associated with hazard ratios for mortality of 1.0048 (95% confidence interval [CI]: 1.0026, 1.0070), 1.0021 (95% CI: 1.0013, 1.0029), and 1.0022 (95% CI: 1.0014, 1.0030), respectively. This translated to 49 annual excess deaths attributable to PM2.5, 21 to ozone, and 22 to NO2 within the cohort. Effects were substantially larger at low exposure levels. PM2.5 and NO2 had greater effects in younger patients, those who received chemotherapy or radiation, and those diagnosed at later stages.
Conclusion: Our findings identified air pollution as a risk factor for mortality in older breast cancer patients. Protective measures and air pollution control strategies may help reduce exposure and improve outcomes.
Journal of the National Cancer Institute , résumé, 2025