Long-Term Exposure to Ambient Air Pollution and Incidence of Postmenopausal Breast Cancer in 15 European Cohorts within the ESCAPE Project

Abstract

Background:Epidemiological evidence on the association between ambient air pollution and breast cancer risk is inconsistent.Objective:We examined the association between long-term exposure to ambient air pollution and incidence of postmenopausal breast cancer in European women.Methods:In 15 cohorts from nine European countries, individual estimates of air pollution levels at the residence were estimated by standardized land-use regression models developed within the European Study of Cohorts for Air Pollution Effects (ESCAPE) and Transport related Air Pollution and Health impacts - Integrated Methodologies for Assessing Particulate Matter (TRANSPHORM) projects: particulate matter (PM) ≤2.5μm, ≤10μm, and 2.5–10μm in diameter (PM2.5, PM10, and PMcoarse, respectively); PM2.5 absorbance; nitrogen oxides (NO2 and NOnormalx); traffic intensity; and elemental composition of PM. We estimated cohort-specific associations between breast cancer and air pollutants using Cox regression models, adjusting for major lifestyle risk factors, and pooled cohort-specific estimates using random-effects meta-analyses.Results:Of 74,750 postmenopausal women included in the study, 3,612 developed breast cancer during 991,353 person-years of follow-up. We found positive and statistically insignificant associations between breast cancer and PM2.5 {hazard ratio (HR)=1.08 [95% confidence interval (CI): 0.77, 1.51] per 5 μg/m3}, PM10 [1.07 (95% CI: 0.89, 1.30) per 10 μg/m3], PMcoarse [1.20 (95% CI: 0.96, 1.49 per 5 μg/m3], and NO2 [1.02 (95% CI: 0.98, 1.07 per 10 μg/m3], and a statistically significant association with NOnormalx [1.04 (95% CI: 1.00, 1.08) per 20 μg/m3, p=0.04].Conclusions:We found suggestive evidence of an association between ambient air pollution and incidence of postmenopausal breast cancer in European women. https://doi.org/10.1289/EHP1742

Exposure to ambient air pollution and the incidence of lung cancer and breast cancer in the Ontario Population Health and Environment Cohort

“…Although three case–control studies observed positive associations with exposure to PM 2.5 or NO 2 , our results are similar to several other recent cohort studies which found limited evidence linking incident breast cancer to PM 2.5 or NO 2. For example, no association with PM 2.5 was observed in the Danish Nurse Cohort Study (HR = 0.99; 95% CI: 0.94–1.10 per IQR of 3.3 μg/m 3 ; 1,145 cases) and in the US Sister Study (HR = 1.03; 95% CI: 0.96–1.11 per IQR of 3.6 μg/m 3 ; 1,749 cases) . In addition, the European Study of Cohorts of Air pollution Effects reported no association between incident breast cancer and exposure to NO 2 with a HR of 1.02 (95% CI: 0.98–1.07 per 10 μg/m 3 ; 3,612 cases) .…”

“… For example, no association with PM 2.5 was observed in the Danish Nurse Cohort Study (HR = 0.99; 95% CI: 0.94–1.10 per IQR of 3.3 μg/m 3 ; 1,145 cases) and in the US Sister Study (HR = 1.03; 95% CI: 0.96–1.11 per IQR of 3.6 μg/m 3 ; 1,749 cases) . In addition, the European Study of Cohorts of Air pollution Effects reported no association between incident breast cancer and exposure to NO 2 with a HR of 1.02 (95% CI: 0.98–1.07 per 10 μg/m 3 ; 3,612 cases) . The lack of association observed in our study and in these previous cohort studies might be attributable to the absence of data on early‐life air pollution exposures.…”

“…These effects may potentially increase the risk for breast cancer, but current epidemiological evidence on chronic exposure to air pollution and the incidence of breast cancer is scarce and inconsistent. For example, positive and statistically significant associations with PM 2.5 or NO 2 were reported in four studies, whereas null associations were found in others . Additionally, less is known about whether exposure to oxidant gases (e.g., NO 2 and O 3 ) may modify the risk for breast cancer in association with PM 2.5 .…”

Association of breast cancer risk with polymorphisms in genes involved in the metabolism of xenobiotics and interaction with tobacco smoking: A gene‐set analysis

“…The well‐established risk factors for breast cancer related to hormone and reproduction or obesity account for only a minority of the diagnoses . Exposures to environmental chemicals such as PCBs, organochlorine pesticides, dioxins, PAHs, organic solvents or air pollutants are also suspected to account for part of the breast cancer incidence . Some of these chemicals such as PAHs, aryl amines, and N‐nitrosamines are metabolized and activated in mammary gland cells and may induce mammary tumors in experimental animals .…”

Environmental noise and breast cancer risk?

“…Environmental air pollution -including exposure to polyaromatic hydrocarbons (PAH), which may be correlated with traffic noise (24) -has also been suggested as a risk factor for breast cancer (25), though the association is not clear (26). Regardless, attempts to adjust for this obvious potential confounder should also be included in future studies on noise and cancer.…”