Estrogen-alone hormone therapy does not increase the risk of breast cancer in postmenopausal women, according to an updated analysis of the breast cancer findings of the Women's Health Initiative (WHI) Estrogen-Alone Trial.
The results contrast with the previously reported WHI Estrogen plus Progestin Trial, which found an increase in breast cancer over about 5 years among those taking combined hormone therapy. Over an average of about 7 years of follow-up, study participants taking estrogen had fewer breast cancer tumors than those in the placebo group.
"Longer follow-up is needed to fully explain the reduced number of breast cancers in women taking estrogen. However, this new analysis does not alter the overall conclusion from the WHI that hormones, including estrogen-alone and estrogen plus progestin, should not be used for the prevention of chronic disease," said NHLBI and WHI Director Elizabeth G. Nabel, M.D. "The findings still support current recommendations that hormone therapy should only be used to treat menopausal symptoms and should be used at the smallest effective dose for the shortest possible time."