Body type and race are factors in hormone therapy risks for women

NEW YORK (Reuters Health) - For a woman contemplating taking hormone replacement therapy (HRT), the increase in breast cancer risk she faces may depend on her individual body type, race and ethnicity, according to new U.S. research.

In a large new study of women on HRT, slim and normal-weight women with dense breast tissue saw a nearly 50 percent increase in breast cancer risk, while women who were black or overweight with less-dense breast tissue showed no risk increase at all.

"With many medications, the effects aren't the same for everybody, either for prevention or treatment," Dr. Dezheng Huo of the University of Chicago, one of the new study's authors, told Reuters Health.

For decades, menopausal women routinely took estrogen alone or estrogen with progestin to cope with hot flashes and night sweats. Conventional medical wisdom held that HRT, because it kept estrogen levels high, would also protect the heart and maintain bone strength.

But the Women's Health Initiative (WHI), a large, long-term clinical trial, found that HRT did not reduce women's heart attack risk and actually raised the risk of stroke. Moreover, that study showed a 24 percent increased risk of invasive breast cancer in women who took estrogen and progestin.

Since 2002, when the WHI findings were released, the number of women using HRT has fallen sharply, but it remains the most effective treatment for menopausal symptoms and many doctors still prescribe it for short-term use.

And several recent studies have suggested that breast cancer risks associated with hormone therapy may vary based on factors like body mass index (BMI) - a measure of weight in relation to height - and ethnicity.

To investigate further, Huo and his team analyzed data from the National Cancer Institute's Breast Cancer Surveillance Consortium, which includes 1,642,824 screening mammograms and 9,300 breast cancer cases.

In their analysis, they looked at women 45 years old and older and considered the women's ethnicity and BMI, as well as their breast density. Greater breast density means a woman has more breast tissue and connective tissue than fatty tissue, while lower density means she has more fatty tissue relative to breast and connective tissue.

Women with extremely dense breasts, who represent about 15 percent of the general female population, are known to have a greater risk of breast cancer.

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Body type and race are factors in hormone therapy risks for women