Mortality from breast cancer is markedly higher in African American women as compared to white women in the U.S., in part because they are more likely to be diagnosed with ER-negative tumors, which are more aggressive and difficult to treat. African American women are also diagnosed with breast cancer at younger ages.
Researchers from Boston University's Slone Epidemiology Center used 18 years of data from 57,708 African American women enrolled in the Black Women's Health Study, a follow-up study of the health of African American women in progress since 1995. They evaluated the relation of reproductive factors, measures of body size, and other factors to incidence of ER-negative and ER-positive breast cancer in both younger and older women. "Very little is known about how young women can reduce their personal risk of ER-negative breast cancer," said Kimberly Bertrand, ScD, epidemiologist at the Slone Epidemiology Center at Boston University and assistant professor of medicine at Boston University School of Medicine, who led this study. "Most exciting among our findings is that two of the factors we found to be important -- breastfeeding and higher waist-to-hip ratio -- are modifiable, which suggests opportunities for risk reduction or prevention."
Funding for this study was provided by the National Cancer Institute (grants CA058420, CA164974, CA151135, and CA182898).