Mordukhovich, I; Beyea, J; Herring, AH; Hatch, M; Stellman, SD; Teitelbaum, SL; Richardson, DB; Millikan, RC; Engel, LS; Shantakumar, S; Steck, SE; Neugut, AI; Rossner, P; Santella, RM; Gammon, MD
BACKGROUND: Polycyclic aromatic hydrocarbons (PAHs) are widespread environmental pollutants, known human lung carcinogens, and potent mammary carcinogens in laboratory animals. However, the association between PAHs and breast cancer in women is unclear. Vehicular traffic is a major ambient source of PAH exposure.
OBJECTIVES: Our study aim was to evaluate the association between residential exposure to vehicular traffic and breast cancer incidence.
METHODS: Residential histories of 1,508 breast cancer cases and 1,556 controls were assessed in a population-based investigation conducted in 1996-1997. Traffic exposure estimates of benzo[a]pyrene (B[a]P), as a proxy for traffic-related PAHs, for the years 1960-1995 were reconstructed using a model previously shown to generate estimates that are consistent with measured soil PAHs, PAH-DNA adducts, and CO readings. Associations between vehicular traffic exposure estimates and breast cancer incidence were evaluated using unconditional logistic regression.
RESULTS: The odds ratio (95% CI) was modestly elevated by 1.44 (0.78, 2.68) for the association between breast cancer and long-term 1960-1990 vehicular traffic estimates in the top 5%, compared with below the median. The association with recent 1995 traffic exposure was elevated by 1.14 (0.80, 1.64) for the top 5%, compared with below the median, which was stronger among women with low fruit/vegetable intake (1.46 (0.89, 2.40), but not among those with high intake (0.92 (0.53, 1.60)). Among the subset of women with information regarding traffic exposure and tumor hormone receptor subtype, the traffic-breast cancer association was higher for those with estrogen/progesterone-negative tumors (1.67 (0.91, 3.05) relative to controls), but lower among all other tumor subtypes (0.80 (0.50, 1.27) compared with controls).
CONCLUSIONS: In our population-based study, we observed positive associations between vehicular traffic-related B[a]P exposure and breast cancer incidence among women with comparatively high long-term traffic B[a]P exposures, although effect estimates were imprecise.
