Environment and Cancer Epidemiology

National Institute Of Environmental Health Sciences

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Abstract

To investigate the effects of environmental factors on breast cancer risk we have conducted a number of high-quality population-based studies. We have been working in the Sister Study cohort, a large prospective study of women who have a sister with breast cancer. The Sister Study is a study of over 50,000 women across the United States which has information on exposure to residential criteria air pollutants, including fine particulate matter (PM2.5). PM2.5 is a heterogeneous mixture of pollutants that varies geographically. We previously evaluated the role of PM2.5 and other air pollutants in relation to breast cancer risk in the Sister Study (PMID: 315966020) as well as in another large prospective cohort, the Black Womens Health Study (PMID: 33387538); in both cohorts we observed substantial geographic heterogeneity in associations between PM2.5 and breast cancer risk. We have recently extended this work in the large NIH-AARP cohort where we observed a significant positive association between PM2.5 and breast cancer risk and a suggestion of heterogeneity in the association across catchment areas (under revision). Little is known about biologic pathways that may underlie associations between air pollution and breast cancer risk. In a sample of women who donated normal breast tissue to the Komen Tissue Bank, we observed that those living in areas with higher PM2.5 had breast tissue characteristics consistent with a higher risk of developing breast cancer (PMID: 37224678). Indoor air pollution may be another important source of exposure to pollutants yet it is not well understood about how indoor air pollution may be related to cancer risk. We previously reported that use of indoor stoves/fireplaces was related to a higher risk of breast cancer (PMID: 28728136) and have recently expanded upon this work to demonstrate that use of indoor stove/fireplaces is also related to lung cancer risk among women in the Sister Study (PMID: 37542784). To better understand the impact of point sources of chemical exposures, we evaluated residential proximity to EPA Superfund sites and toenail metal levels. We observed that women who lived closer to lead or cadmium sites were more likely to have higher toenail metal levels and that this association was strongest for non-Hispanic Black women compared to non-Hispanic white women (PMID: 36917478). Following up on our study that observed a higher risk of breast cancer for adult use of permanent hair dye and chemical straighteners (PMID: 31797377), we further explored how adolescent use of these products may be related to breast cancer risk. Extending this research to other hormone-related cancer types, we have found that frequent straightener use was also associated with an elevated risk of ovarian cancer (PMID: 34173819) and most recently uterine cancer (PMID: 36245087).