The pregnancy exposome and premenopausal breast cancer risk - implications for future risk stratification and cancer prevention

More than 20% of all breast cancer cases in Sweden occur before menopause, and rates are increasing. Premenopausal breast cancer tend to be aggressive and has distinct risk factors. Reducing these risk factors, as well as identifying women at high risk could have major impact on future cancer prevention.

Pregnancy constitutes a sensitive time-period when the breast is particularly vulnerable to environmental exposures that may alter glandular morphology and function. The built environment (living environment, work environment) and the chemical environment (external chemicals) are both likely to contain exposures that modify breast cancer risk. Examples include air pollution, and Per- and polyfluoroalkyl substances (PFAS) that have been shown to impact breast development during pregnancy. However, detailed studies on premenopausal breast cancer are lacking, as is knowledge about the molecular underpinnings linking exposures occurring during windows of susceptibility to cancer risk.

The objective in this proposal is to determine if environmental exposures, occurring during pregnancy are associated with risk of premenopausal breast cancer. The rationale for the proposed research program is that its successful completion could identify important, and potentially modifiable, risk factors for premenopausal breast cancer that can be targeted during pregnancy to reduce cancer incidence.

The specific aims are:
1) Determine if the built environment (air pollution, traffic noise, green spaces) during pregnancy is associated with risk of premenopausal breast cancer.

2) Determine if the chemical environment (e.g. endocrine disrupting chemicals) during pregnancy is associated with risk of premenopausal breast cancer.