April 8, 2008 / 8:01 PM / 11 years ago

Estrogen raises risk of benign breast disease

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.


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

While the study sheds more light on the risks linked with taking estrogen therapy, Rohan thinks it will not change practices much because women must already be mindful of the risks of HRT.

“Each and every person who is a candidate for taking hormone therapy really needs to weigh the risks and benefits. You might say, this is one additional risk,” Rohan said in a telephone interview.

But Dr. Hugh Taylor of the Yale University School of Medicine who had seen the study, said the increase in benign proliferative breast disease may simply reflect the fact that breast tissue responds to estrogen.

“It sounds scarier than it is,” Taylor said in a telephone interview. “Breasts are supposed to grow in response to estrogen. That is what a normal healthy breast does,” he said.

Wyeth said in a statement the study reflected only a small subset of the more than 10,000-patient study, which found no increased risk of breast cancer.

Rohan said it may be that women in the study had not been followed long enough for breast cancer to develop, but it was not clear from the study whether these non-cancerous growths would develop into cancer.

The Women’s Health Initiative only looked at women taking Premarin-based products, and most were on average 10 years past menopause. Other estrogen therapies are now available at lower doses and some studies have suggested that women who start HRT when they are younger, right around menopause, have fewer health risks from HRT.

Editing by Maggie Fox

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