(RxWiki News) We wouldn’t be women without estrogen. The hormone controls our sexual features and our ability to carry children. This hormone also drives the most common forms of breast cancer.
For postmenopausal women, having lower estrogen levels is thought to lower breast cancer risks.
A recent study looked at how exercise affects estrogen levels in postmenopausal women. Physical activity resulted in lower levels of estrogens and estrogen by-products.
This study builds on an expanding knowledge base that suggests physical activity may lower a woman’s risk of developing breast cancer.
"Be active to help protect your body against disease."
Unlike previous research, Cher Dallal, PhD, a National Cancer Institute (NCI) cancer prevention fellow, and colleagues looked at how exercise affected how the body breaks down estrogen.
The process is known as estrogen metabolism and results in a number of different kinds of molecules called metabolites.
The researchers studied 540 postmenopausal women who had participated in National Cancer Institute (NCI) Polish Breast Cancer Study, conducted between 2000 and 2003.
To measure overall activity, the participants wore a small device on their waists during walking hours for seven days. Compared to self-reported activity, the devices provide a more accurate measure of activity called “accelerometer-measured activity.”
The women also provided urine samples every 12 hours. The samples were tested for “parent” estrogens and 13 metabolites.
“This is the first study to consider the relationship between accelerometer-measured activity and a panel of estrogen metabolites measured in urine,” according to Dr. Dallal.
“We hoped by using direct measures to examine this relationship that we could improve our knowledge of how these factors may influence cancer risk among postmenopausal women.”
Increased physical activity was associated with lower levels of both parent estrogens and four types of estrogen metabolites.
“Our findings with accelerometer-measured physical activity are consistent with prior studies reporting a reduction in estrogen levels with increased activity,” the authors concluded.
These findings, presented at the American Association for Cancer Research Annual Meeting 2013, add to the understanding of links between breast cancer risks and physical activity.
All research is considered preliminary before being published in a peer-reviewed journal. There were no conflicts of interest disclosed.