Air pollution and Breast Cancer: A Review

Breast cancer is the most common cancer diagnosed among US women. Air pollution is a pervasive mixture of chemicals containing carcinogenic compounds and chemicals with endocrine disrupting properties. In the present review, we examine the epidemiologic evidence regarding the association between air pollution measures and breast cancer risk.

We identified seventeen studies evaluating the risk of breast cancer associated with air pollution. A higher risk of breast cancer has been associated with nitrogen dioxide (NO₂) and nitrogen oxides (NO_x) levels, both of which are proxies for traffic exposure. However, there is little evidence supporting a relationship for measures of traffic count or distance to nearest road, or for measures of particulate matter (PM), except potentially for nickel and vanadium, which are components of PM₁₀. Hazardous air toxic levels and sources of indoor air pollution may also contribute to breast cancer risk. There is little existing evidence to support that the relationship between air pollution and breast cancer risk varies by either menopausal status at diagnosis or combined tumor hormone receptor subtype defined by the estrogen receptor (ER) and progesterone receptor (PR).

Epidemiologic evidence to date suggests an association between breast cancer risk and NO₂ and NO_x, markers for traffic-related air pollution; although there was little evidence supporting associations for proxy measures of traffic exposure or for PM. More research is needed to understand the role of specific PM components and whether associations vary by tumor receptor subtype and menopausal status at diagnosis.