Hormone Supplements Linked to Higher Risk of Breast Cancer in African-American Women.
Postmenopausal African-American women who use female hormone supplements containing estrogen and progestin (“combination” therapy) are at an increased risk for estrogen receptor positive breast cancer, according to a new study co-authored by School of Public Health researchers.
The study, published in the Journal of the National Cancer Institute, found the overall increase in risk was 50 percent, with greater increases for recent and long-term users.
Prior epidemiologic studies have been based largely on white women. In those studies, use of combination therapy was associated with an increased risk of estrogen receptor positive breast cancer, the most commonly occurring breast cancer subtype, which is known to be sensitive to hormonal factors. Whether postmenopausal hormone therapy has the same effects in black women has been unknown up to this point, since the few studies that had researched this population had produced conflicting data.
Researchers from the Slone Epidemiology Center at BU led an investigation of this association, using data from four large studies of black women included in the AMBER (African American Breast Cancer Epidemiology and Risk) Consortium, led by investigators at BU, Roswell Park Cancer Institute, and the University of North Carolina. Two types of postmenopausal female hormone use, combination therapy and use of estrogen alone were assessed in relation to risk of estrogen receptor positive and estrogen receptor negative breast cancer.
Similar to findings in white women, use of combination therapy was associated with increased risk of estrogen receptor positive breast cancer, with the risk increasing as the duration increased. The risk declined after cessation of use, but was still somewhat elevated up to 10 years later. There was no increase in risk associated with use of estrogen alone, nor was there any increase in risk of estrogen receptor negative breast cancer associated with use of either combination therapy or estrogen alone.
“The present findings establish that combination therapy in black women is associated with increased risk of estrogen receptor positive breast cancer, similar to the pattern in white women,” said corresponding author Lynn Rosenberg, associate director of the Slone Epidemiology Center and professor of epidemiology at SPH. “Our findings highlight the importance of black women limiting their use of combination therapy.”
According to Rosenberg, the latter point is particularly important because recent national cancer statistics indicate that breast cancer incidence has been increasing among African-American women and converging to the rate of white women, while death rates continue to diverge between the groups.
Co-authors on the study include Julie Palmer, senior epidemiologist at Sloneand professor of epidemiology at SPH. Funding for the study was provided by the National Institutes of Health, the Breast Cancer Research Foundation (CBA), and the University Cancer Research Fund of North Carolina.