Polycyclic Aromatic Hydrocarbons (PAHs) and Breast Cancer Risk

Women serving in the US military get breast cancer more often than civilian women of the same age. It is not well understood why these young women are at increased risk for developing breast cancer. One hypothesis is that women in the military may be exposed to chemicals that increase their risk to breast cancer. Many women deployed to Iraq or Afghanistan were exposed to polycyclic aromatic hydrocarbons (PAH) from burn pits or other combustion of fossil fuels. These PAHs are formed when things are burned and have been considered to be endocrine-disrupting chemicals in that they can have an effect on a woman's hormonal system.

The military has maintained a large collection of stored serum from blood with multiple tubes for every active duty member of the military since the 1990s. Additional samples are obtained at physical exams conducted every 2 years and pre- and post-military deployment. Health and medical information can be linked to these serum samples. We will identify around 1500 women who had a new breast cancer diagnosis between 2000-2017 while on active duty in the US military. We will then select a woman in the military of the same age, race, and branch of service as each case who had not developed breast cancer at the time of case's diagnosis. In collaboration with our Partnering Principal Investigator, Dr. Mary Beth Terry, with the laboratory at the Columbia University, we will use blood serum samples collected before breast cancer diagnoses for all of the cases and the same number of samples for controls to assess a marker of past PAH exposures (PAH-adduct levels). We will use a post-diagnostic sample to measure small genetic variations in DNA that may increase a woman's susceptibility to the environmental exposures.

We will use this information to:

(1) Evaluate what factors determine PAH-adduct levels among active duty US military women.

(2) Determine the associations between PAH-adduct levels and breast cancer risk.

(3) Evaluate whether PAH-adducts effects on breast cancer risk involves genetic variation related to various biologic and metabolic pathways.

From this study we will be able to tell whether women with higher exposure levels to PAH-adducts are at increased risk of developing breast cancer and we will understand some of the biological pathways involved.