Hormones raise breast cancer risk quickly

WASHINGTON – Hormone replacement therapy can raise the risk of an uncommon type of breast cancer fourfold after just three years, U.S. researchers reported on Monday.

They found women who took combined estrogen/progestin hormone-replacement therapy for three years or more had four times the usual risk of lobular breast cancer.

Their study, published in the January issue of Cancer Epidemiology, Biomarkers and Prevention, is one of dozens trying to paint a clearer picture of what dangers might come from taking HRT to treat menopause symptoms.

“Previous research indicated that five or more years of combined hormone-therapy use was necessary to increase overall breast-cancer risk,” Dr. Christopher Li of the Fred Hutchinson Cancer Research Center, who led the study, said in a statement.

“Our study, the first specifically designed to evaluate the relationship between combined HRT and lobular breast cancers, suggests that a significantly shorter length of exposure to such hormones may confer an increased risk.”

Lobular breast cancer accounts for about 10 percent of invasive breast cancer — the kind that threatens to spread — according to the American Cancer Society.

It can be treated with hormone-based therapies such as tamoxifen, but the tumors are more difficult to detect by mammograms, meaning it is often diagnosed in more advanced stages.

Li’s team asked more than 1,500 post-menopausal women in western Washington about whether they had used HRT. Of the women, 1,044 had breast cancer and 469 did not.

They found that women currently taking HRT were about three times as likely as other women to be among the cancer patients and those who used combined HRT for three or more years had a higher risk of lobular cancer.