ASPO Abstracts
Hazardous Metallic Air Toxics and Breast Cancer Risk in a Nationwide Cohort Study
Category: Early Detection & Risk Prediction, Molecular Epidemiology & Environment
Conference Year: 2018
Abstract Body:
Purpose. Heavy metals have carcinogenic and estrogenic properties, however, little is known about the relationship between airborne metals and breast cancer. We evaluated the risk of breast cancer in relation to metallic air toxics individually and simultaneously in a U.S wide cohort. Methods. Sister Study participants (n=50,884), breast cancer-free women with a sister with breast cancer, were recruited from 2003-2009. The 2005 Environmental Protection Agency National Air Toxic Assessment’s census-track concentration estimates of heavy metals (antimony, arsenic, cadmium, chromium, cobalt, lead, manganese, mercury, nickel, and selenium) were matched to participants’ enrollment residence. We used Cox regression to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (95% CI) for the association between quintiles of individual metals and breast cancer and used weighted quantile sum (WQS) regression to model the association between the metal mixture and breast cancer. Results. 2,756 breast cancer cases were diagnosed during follow-up (mean=7.4 years). In individual chemical analyses comparing the highest to lowest quintiles, postmenopausal breast cancer risk was elevated for mercury (HR=1.25, 95%CI: 1.08-1.46), cadmium (HR=1.11, 95%CI: 0.96-1.28), and lead (HR=1.14, 95%CI: 0.98-1.32). The WQS index was significantly associated with postmenopausal breast cancer (odds ratio (OR)=1.07, 95%CI: 1.01-1.13). Consistent with the individual analysis, the most highly weighted chemicals for predicting postmenopausal breast cancer risk were lead, cadmium and mercury. Results were attenuated for overall breast cancer. Conclusions. Higher levels of some airborne metals, specifically mercury, cadmium and lead, were associated with a higher risk of postmenopausal breast cancer.
Keywords: breast cancer, air pollution, heavy metals, mixtures