Exercise lowered estrogens, breast cancer risk in postmenopausal women

Results of a study presented at the American Association for Cancer Research Annual Meeting have given researchers a better idea of the potential mechanisms at play in the link between physical activity and low breast cancer risk in postmenopausal women, according to a press release.

Increased physical activity was associated with lower levels of estradiol and estrone and with lower levels of four specific estrogen metabolites. Study researcher Cher M. Dallal, PhD, said in the press release, however, that more data on estrogen metabolism are needed to understand the role of metabolites in mediating breast cancer risk.

The study included healthy, postmenopausal women not taking hormone therapy (n=540) who were enrolled in the National Cancer Institute (NCI) Polish Breast Cancer Study, which was conducted between 2000 and 2003. Using accelerometers, researchers measured physical activity for 7 days and collected a 12-hour urine sample to test for estradiol and estrone plus 13 various estrogen metabolites using an NCI-developed novel assay.

According to Dallal, who is also an NCI cancer prevention fellow, physical activity-induced estrogen metabolism may explain previous study findings linking physical activity to a reduced risk for breast cancer in this patient population.

“By using these new tools to study the relationship between activity and estrogen metabolism, we hope to get closer to uncovering the combination of parent estrogens, metabolites and metabolism pathways that are related to a lower-risk profile of breast cancer,” Dallal said in the release.

For more information:

Dallal CM. Abstract #2519. Presented at: the American Association for Cancer Research Annual Meeting 2013; April 6-10, 2013; Washington, D.C.

Disclosure: Dallal reports no relevant financial disclosures.