Black women have nearly a three-fold increased risk of triple negative breast cancers, according to a new study.
These types of cancer have a poor prognosis.
The analysis of nearly 200,000 patients who received mammograms between 2006 and 2015 across three US health systems underscores the importance of understanding the heterogeneity of breast cancer risk factors for women of differing races, ages, and disease subtypes.
The study appears in Cancer Medicine.
The cohort included 29,822 (15%) Black women—a group historically understudied in cancer research. While it is known that Black women have a higher risk of this type of breast cancer, the magnitude of the risk researchers found in this study is of particular interest, given the study’s comprehensive adjustment for breast cancer risk factors in a screened population.
Additionally, the researchers found that triple negative breast cancers were less likely to be screen detected and more likely than other subtypes to be diagnosed as interval cancers. Higher breast density was associated with increased risk of all four tumor subtypes, with a stronger association among premenopausal women for ER/PR+HER2- and TNBC.
In a separate study led by the same group, the researchers looked further at risk factor among Black women. They found that breast density was more strongly associated with TNBC than other subtypes, and obesity was associated with greater risk of TNBC among this group. Those findings appear in Breast Cancer Research and Treatment.
“The risk prediction models available are about 60% accurate for predicting risk of breast cancer,” says Anne Marie McCarthy, an assistant professor of epidemiology at the University of Pennsylvania.
“In our studies, we see clear differences in risk factors across these types of breast cancers, and we need to do a better job of identifying how we can accurately predict risk for women, particularly for women of color.”