Aug. 14, 2012, 11:06 a.m.
Exposure to hormones, specifically estrogen, increases a women's risk of developing breast cancer. Throughout life, women are exposed to hormones. From their first mentrual period to the onset of menopause, estrogen and progesterone stimulate normal breast cells. It is this lifetime exposure to ovarian hormones that is believed to put a woman at risk for breast cancer.