Combination Therapy Raises Breast Cancer Risk in Black Women, Study Says

Studies have long shown a higher risk in white women—so why have African Americans not been studied?

Lynn Rosenberg

Lynn Rosenberg. Photo provided to

A new study from the Boston University School of Medicine (BUSM) found that postmenopausal African American women taking a certain type of hormone supplement are at a heightened risk of breast cancer.

But what’s arguably more interesting than the result is how long it took to get there. Indeed, many past studies have shown that white women taking hormone supplements containing both estrogen and progestin—a regimen called combination therapy, typically prescribed to manage the effects of menopause—are more likely to develop estrogen receptor positive breast cancer. Research about how combination therapy affects black women, however, has been far slower to accumulate.

“This is the first study to really provide some clear-cut, rather definitive evidence on the association among black women,” says Lynn Rosenberg, corresponding author and principal investigator of the Black Women’s Health Study. “It took a very long for there to be any awareness that these women weren’t being studied and that they should be studied.”

Rosenberg explains that, in the past, many researchers simply went to hospitals and asked to enroll patients in studies, which often led to relatively uniform subject populations. “The vast majority of women in those hospitals would have been white women, because the vast majority of the women in the United States are white,” she explains. “You would end up with a study where there weren’t enough women in the minority groups to say anything about them separately.”

Rosenberg and her colleagues decided to change that. They analyzed data from four major studies included in the African American Breast Cancer Epidemiology and Risk (AMBER) Consortium, including Rosenberg’s Black Women’s Health Study. They found that estrogen-only hormone supplements did little to affect breast cancer risk, but combination therapy upped odds of getting estrogen receptor positive cancer by as much as 50 percent.

The findings are important for all women, but take on particular gravity given that breast cancer rates seem to be rising in African American women, who also tend to develop more aggressive sub-types of breast cancer than white women.

“I think this is just one more article that will help to make that change, because this is a preventable cause of breast cancer,” Rosenberg says. “It would be a very good idea if women were not using combination therapy, or at least not for very long periods of time.”