Washington, Apr 9 : Postmenopausal women taking estrogen therapy are increasing their risk of developing specific types of benign breast disease, says a new study.
Women who take conjugated equine estrogen, a commonly prescribed form of estrogen, are at an increased risk of developing benign proliferative breast disease, a condition that may give rise to breast cancer.
For the study, the researchers examined 10,739 postmenopausal women with hysterectomy who were given either conjugated equine estrogen or a placebo.
To determine whether the hormone increases the risk of benign proliferative breast disease, the team of researchers led by Tom Rohan, M.D., Ph.D., of the Albert Einstein College of Medicine in New York identified and examined non-cancerous breast biopsies in each of the Women's Health Initiative trial arms.
The team identified 232 cases of benign proliferative breast disease, with 155 cases among the women who took estrogen supplements and 77 in the placebo group.
The risk of developing benign disease increased by more than double for women taking conjugated equine estrogen, compared with those taking a placebo.
According to the authors, benign proliferative breast disease without atypia, proliferative disease with atypia, and in situ cancer represent successive steps preceding the development of invasive breast [cancer]. In keeping with this hypothesis, women with benign proliferative breast disease have an increased risk of subsequent breast cancer.
The study is published online April 8 in the Journal of the National Cancer Institute.