Environment/Climate Change
Ambient air pollution and mortality in older breast cancer patients Yaguang Wei* Yaguang Wei Edgar Castro Kanhua Yin Min Zhang Hannah Thompson Joel Schwartz
Importance: Air pollution is likely associated with increased breast cancer mortality due to its carcinogenic properties and the increased sensitivity of patients to environmental stressors. However, robust and large-scale evidence remains limited.
Objective: To evaluate associations between annual exposures to fine particulate matter (PM2.5), warm-season ozone, and nitrogen dioxide (NO2), three major regulated air pollutants, and mortality in a large cohort of senior breast cancer patients following diagnosis.
Design, Setting, and Participants: An open cohort constructed using SEER-Medicare data, including Medicare beneficiaries aged ≥65 years with primary diagnosis of breast cancer between 2000–2016.
Exposures: Spatio-temporal estimates of annual PM2.5, warm-season ozone, and NO2 were obtained using hybrid models at 1-km² grid resolution across the contiguous US. The estimates were aggregated and linked to patients’ residential ZIP codes as proxy exposure measures.
Main Outcome: A three-pollutant Cox proportional hazard model was fitted to estimate the hazard rate of mortality per unit increase in exposures, adjusting for demographics, cancer stage, treatments, marital status, comorbidities, meteorological conditions, and neighborhood characteristics.
Results: Among 593,333 patients included in the study, a 1-µg/m³ increase in annual PM2.5, 1-part-per-billion (ppb) increase in warm-season ozone, and 1-ppb increase in NO2 were associated with hazard ratios of 1.0053 (95% CI: 1.0031–1.0075), 1.0023 (95% CI: 1.0015–1.0032), and 1.0020 (95% CI: 1.0012–1.0027) for mortality, respectively. The effects were larger at low exposure levels. Younger patients, patients diagnosed at later stages, and those who received chemotherapy or radiation were more susceptible to the effects.
Conclusions: Our findings on chronic effects of air pollution on breast cancer mortality suggests that improving air quality would help mitigate the significant and escalating disease burden.