Study Disputes Link Between Breast Cancer, Estrogen

Less than a month after researchers reported that taking estrogen during menopause may increase the risk of breast cancer, a new study indicates that there is no such danger.

The lead authors of both studies say more research is needed, though both stand by their findings.

“I know there’s a lot of confusion,” said University of Washington epidemiologist Janet Stanford, lead author of the new study.

Stanford said women should discuss their medical histories with their doctors before deciding whether to use hormones during menopause.

Hormone replacement therapy, using estrogen alone or with progestin, is often prescribed to alleviate the hot flashes and other symptoms of menopause as well as to reduce the risk of heart disease and brittle bones.

Hormone supplements can cut in half the risk of heart disease, the leading cause of death for women as well as men. They have a similar effect on fractures.

Doctors have long suspected that estrogen, a female sex hormone, may play a role in the development of breast cancer. Women with longtime exposure to increased estrogen levels--those who begin menstruating early or go through menopause late--face a higher breast cancer risk.

But doctors have debated for decades whether there is a similar link involving hormones given to women when their natural estrogen production slows down.

Stanford’s study, published in today’s Journal of the American Medical Assn., found that menopausal women who take estrogen alone or with progestin face no increased risk of breast cancer.

The results are based on medical histories of 1,029 Seattle-area women ages 50 to 64. About half had been diagnosed with breast cancer.

Use of the combined therapy for eight years or more “was associated with, if anything, a reduction in the risk of breast cancer,” and estrogen alone used for 20 years or more showed no increased risk, they said.