Estrogen, a female hormone that is found naturally in the body, plays an important role in breast cancer. Studies have shown that the risk of breast cancer is increased among postmenopausal women who have high levels of one type of estrogen (estradiol) circulating in their bloodstream. In an analysis that combined data from nine studies, the risk of breast cancer was twice as high among women with higher levels of estradiol compared to women with lower levels [50].
To date, blood estrogen levels are not used clinically to assess a woman's risk of breast cancer. However, there are certain markers that can be used to estimate how much estrogen a woman has been exposed to in her lifetime. For example, a woman's age at her first period and her age at menopause can indicate how many years she was exposed to the higher estrogen levels associated with menstrual cycles.
A woman's blood estrogen level is influenced by a number of factors, some of which are within her control. For example, a woman can lower her estrogen levels by maintaining a healthy weight, limiting alcohol intake, being physically active and avoiding postmenopausal hormones. All of these steps can help lower the risk of breast cancer as well as other chronic diseases.
Updated 09/14/09
