Long-term atmospheric exposure to PM2.5 and PM10 and breast cancer risk in a case-control study nested in the French E3N cohort from 1990 to 2011

BACKGROUND/AIM Breast cancer is one of the most prevalent cancers in women and its incidence increased in France during the past thirty years. Known risk factors include ageing, genetic, reproductive, anthropometric, and lifestyle factors. Since they fail to totally explain the observed risk increase, it has been hypothesized that some of this increase could be related to environmental exposure to endocrine disrupting chemicals. Among those, particulate matters (PM) have been pointed out by epidemiological studies due to their potential endocrine disrupting and carcinogen properties We aimed to estimate the association between PM2.5 and PM10 exposure and the risk of breast cancer among women in a case-control study nested in the French E3N cohort. METHODS Our study focused on 5222 invasive breast cancer cases diagnosed between 1990 and 2010 and 5222 randomly selected controls matched to cases. Assessment of PM2.5 and PM10 exposures were estimated by land use regression (LUR) models and assigned to the geocoded residential postal codes of participants for each year from recruitment 1990 through 2011. We estimated odds ratios (OR) and 95% confidence intervals (CI) for breast cancer using conditional adjusted logistic regression models. RESULTS We found a positive association between breast cancer risk and PM2.5 (OR=1.15, 95%CI: 1.00-1.31, per 10µg/m3) and PM10 (OR=1.07, 95% CI: 0.99-1.15). These results were confirmed estimating PM2.5 and PM10 exposure with a chemistry transport model (CHIMERE). CONCLUSIONS We found suggestive evidence of an association between air pollution exposure and incidence of breast cancer risk in French woman KEYWORDS Particulate matters, breast cancer, air pollution, risk factor, land use regression models