We have long known that African-American women who have breast cancer have a higher risk of death from the disease. Now, we have learned that gene flaws that raise the risk of breast cancer are surprisingly common among blacks who have the disease. A study reported today found that roughly 1 in 5 of these women have BRCA mutations, a problem we typically associate with women of Eastern European Jewish descent. These findings may help to explain why black women have higher rates of breast cancer at young ages, in addition to a higher risk of breast cancer-related death. Dr. Jane Churpek, the study leader, was very surprised by the results.
The study included 249 black breast cancer patients from the Chicago area. Many had breast cancer at a young age, and half had a family history of the disease. Here’s where the investigators went beyond the usual genetic testing: All patients had complete gene sequencing for all 18 known breast cancer risk genes rather than the usual tests that simply try to find a few specific mutations in BRCA genes. The results? Gene flaws were found in 56, or 22% of study participants; 46 involved BRCA1 or BRCA2, and the rest were less commonly mutated genes. Among black women with “triple negative” (estrogen receptor negative, progesterone receptor negative, HER2 negative), or the worst subtype of breast cancer, 30% had harmful mutations.
To me, the results point to the fact that too few African-American women have been included in genetic studies in the past. We really had no clue about the extent of mutations among this population. And if a parent has a BRCA mutation, children have a 50% chance of getting the gene. Today, we have more knowledge about the specifics of the gene problem among African American women with breast cancer. I’m Dr. Michael Hunter.