Estrogen raises risk of benign breast disease

By Julie Steenhuysen

CHICAGO (Reuters) - Women who took a commonly prescribed hormone replacement therapy pill had double the risk of developing benign proliferative breast disease, which may raise the risk of breast cancer, U.S. researchers said on Tuesday.

The study, published in the Journal of the National Cancer Institute, is one of dozens trying to paint a clearer picture of what risks might come from taking hormone replacement therapy, or HRT, to treat menopause symptoms.

Dr. Thomas Rohan of the Albert Einstein College of Medicine in New York and colleagues aimed to see if taking the Wyeth drug Premarin, a form of estrogen derived from the urine of pregnant mares, could raise the risk of these types of non-cancerous breast disease.

They looked at 10,739 women past menopause who had taken part in a highly publicized study known as the Women's Health Initiative or WHI. The women in this part of the study had taken either estrogen alone or placebo and were followed for almost seven years.

While the larger WHI study found that women who took combination hormone replacement therapy had a higher risk of heart attack, stroke, breast cancer and other serious conditions, this estrogen-only part of the study in women who had a hysterectomies did not show an increase in breast cancer risk.

Rohan's team identified 232 women from this estrogen-only part of the study who had biopsies for what turned out to be non-cancerous breast disease and who had taken either estrogen alone or a placebo.

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They found 155 cases of non-cancerous proliferative breast disease in women who had taken estrogen, compared with 77 in the placebo group.