Dr. Rowan T. Chlebowski of the Los Angeles Biomedical Research Institute, the lead researcher, and colleagues looked at postmenopausal women with no prior hysterectomy with negative mammograms within two years.
The study, published in the Journal of the National Cancer Institute, found breast cancer incidence was higher in women prescribed estrogen and progestin combined therapy than those where not. Women who started hormone therapy closer to menopause had a higher breast cancer risk with a weakening influence as the time from menopause increased, the study said.
"Because survival after breast cancer diagnosis did not differ between estrogen plus progestin users and non-users, the higher breast cancer incidence of those using estrogen plus progestin may lead to increased breast cancer mortality on a population basis," the authors wrote in the study.
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