CORE RESEARCH PROJECT: Physical Activity, Estrogen Metabolites, and Breast Cancer Risk

FUNDING SOURCE: CDC 1993-1998

PRINCIPAL INVESTIGATOR: Ann Coker, PhD

CO-INVESTIGATORS: Martin Crane, PhD and Mark Davis, PhD

Moderate levels of physical activity have been observed to reduce the risk of breast cancer in two studies. Further corroborating studies are, however, needed. Physical activity could affect breast cancer risk through its influence on endogenous hormones. Bradlow et al. have reported a correlation between the percentage of estradiol (E2), the major estrogen secreted by the ovary, metabolized along the 16A0HE1 pathway and risk of mammary neoplasia.

This pilot study was designed to determine the relationship between physical activity, estrogen metabolism and breast cancer risk. Subjects recruited from the Greenville Hospital System in South Carolina were 100 newly diagnosed breast cancer cases, 100 Tamoxifen Breast Cancer Prevention Trial eligible subjects or Breast Clinic patients (high risk group) and 100 screening mammography clients (low risk group). All subjects provided a urine sample for assessment of the estrogen metabolite ratio, completed a personal interview, and complete a self-administered dietary history questionnaire. Physical activity levels for subjects as young adults and as older adults (within one year of study recruitment) were measured and correlated with the estrogen metabolite ratios and case risk groupings.

If physical activity is associated with breast cancer risk through altering the pathway of estrogen metabolism, primary prevention interventions can be developed to increase physical activity levels among healthy women. Secondary prevention efforts toward reducing the risk of breast cancer recurrence with increased physical activity can also be developed.