Chronic long-term exposure to cadmium air pollution and breast cancer risk in the French E3N cohort
Menée en France à partir de données portant sur 4 059 patientes atteintes d'un cancer du sein et sur 4 059 témoins, cette étude évalue l'association entre une expostion à long terme à une pollution atmosphérique au cadmium et le risque de développer la maladie en fonction du sous-type moléculaire
Cadmium, due to its estrogen like activity, has been suspected to increase the risk of breast cancer, however epidemiological studies have reported inconsistent findings. We conducted a case-control study (4,059 cases and 4,059 matched controls) nested within the E3N French cohort study to estimate the risk of breast cancer associated with long-term exposure to airborne cadmium pollution, and its effect according to molecular subtype of breast cancer (estrogen receptor negative/positive (ER-/ER+) and progesterone receptor negative/ positive (PR-/PR+)). Atmospheric exposure to cadmium was assessed using a Geographic Information System (GIS) based metric, which included subject's residence-to-cadmium source distance, wind direction, exposure duration and stack height. Adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression. Overall, there was no significant association between cumulative dose of airborne cadmium exposure and the risk of overall, premenopausal and postmenopausal breast cancer. However, by ER and PR status, inverse associations were observed for ER- (ORQ5 vs Q1 = 0.63; 95% CI: 0.41-0.95, P trend = 0.043) and for ER-PR- breast tumors (ORQ4 vs Q1 = 0.62; 95% CI: 0.40-0.95, ORQ5 vs Q1 = 0.68; 95% CI: 0.42-1.07, P trend = 0.088). Our study provides no evidence of an association between exposure to cadmium and risk of breast cancer overall, but suggests that cadmium might be related to a decreased risk of ER- and ER-PR- breast tumors. These observations and other possible effects linked to hormone receptor status warrant further investigations. This article is protected by copyright. All rights reserved.