Pre-menopausal African American women have a higher prevalence of basal-like breast tumors than post-menopausal African American and non-African American women, which could contribute to their poorer prognosis, according to a study in the June 7 issue of JAMA.

Breast cancer is composed of an increasing number of recognized biological subtypes. The prognostic importance of this is complicated by many factors, including the observation that differences in clinical outcomes often correlate with race, according to background information in the article. Although breast cancer is less common among African American women, among those who develop it the prognosis is worse. The age-adjusted death rate in the United States from breast cancer in white women is 28.3 deaths per 100,000 compared with 36.4 deaths per 100,000 in African American women. This disparity is particularly pronounced among women younger than 50 years, in whom the death rate is 77 percent higher among African American women compared with white women. Biological differences among breast cancers may reflect genetic influences, differences in lifestyle, or nutritional or environmental exposures.

Lisa A. Carey, M.D., of the University of North Carolina-Lineberger Comprehensive Cancer Center, Chapel Hill, N.C., and colleagues conducted a study of environmental and molecular determinants of breast cancer risk to identify breast tumor subtypes and determine associations between tumor subtypes and race, menopausal status, tumor characteristics, and survival. The Carolina Breast Cancer Study, a population-based study, included 496 incident cases of invasive breast cancer.

The researchers found that one of the more aggressive subtypes, the basal-like breast cancer subtype, was more prevalent among pre-menopausal African American women (39 percent) compared with post-menopausal African American women (14 percent) and non-African American women (16 percent) of any age, whereas the luminal A subtype was less prevalent (36 percent vs. 59 percent-54 percent, respectively). The HER2+/ER- subtype did not vary with race or menopausal status (6 percent-9 percent). In this cohort of patients diagnosed between 1993-96, breast cancer - specific survival differed by subtype, with shortest survival among HER2+/ER- and basal-like subtypes. The basal-like subtype is sensitive to chemotherapy, however unlike the other subtypes there are currently no targeted treatment options for this subtype.

“The high prevalence of basal-like tumors in younger African American women could contribute to their higher breast cancer mortality. Additional studies of long-term survival among patients with specific breast cancer subtypes are needed. Clinical trials aimed at identifying therapeutic approaches to the management of basal-like breast cancer are also needed, especially for young African American women,” the authors conclude.

American Medical Association (AMA)