ASPO Abstracts
Non-metallic hazardous air toxics and breast cancer risk in the Sister Study cohort
Category: Molecular Epidemiology & Environment
Conference Year: 2019
Abstract Body:
Purpose: Some hazardous air toxics are potentially carcinogenic, but are inconsistently associated with breast cancer risk in women. Whether metabolic factors modify these associations is unknown. We focused on 29 non-metallic air toxics classified as mammary gland carcinogens in animal studies.Methods: Participants included 49,718 women from the Sister Study, a United States-based prospective cohort. Census tract air toxic concentration estimates from the 2005 National Air Toxics Assessment were linked to each participant's baseline residential address. Multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox regression, with each air toxic modeled individually. Body mass index (BMI) and physical activity were considered as modifiers. Multipollutant mixtures were identified using classification trees.Results: Over ~8.4 years of follow-up, 2,975 women were newly diagnosed with breast cancer (invasive or ductal carcioma in situ). In individual pollutant models, several air toxics were associated with increased risk; of these, methylene chloride was most strongly and consistently associated with breast cancer overall (HR quintile 4vs1=1.21 (95% CI=1.07-1.38)) and estrogen receptor positive (ER+) invasive breast cancer (HR quintile 4vs1=1.28 (95% CI=1.08-1.52)). For six air toxics (2,4-toluene diisocynate, benzidene, ethylene dichloride, ethylene oxide, hydrazine, and propylene dichloride), associations were stronger among overweight/obese (vs. non-overweight/obese) women (p<0.05). In classification tree multi-pollutant groups related to breast cancer, age, methylene chloride, BMI, and four other air toxics (propylene dichloride, ethylene dibromide, ethylidene dichloride, styrene) were identified.Conclusions: Some non-metallic air toxics, particularly methylene chloride, were associated with elevated risk overall and for ER+ breast cancer. Overweight/obese women may be particularly susceptible to air toxics.
Keywords: air toxics, breast cancer, obesity