Black Women Need Genetic Testing for Breast Cancer Too

A study including  CPS-II/3 survey and blood data finds that both Black and White women need genetic counseling/tests to predict the risk of breast cancer.

The researchers looked in the data from AA women for pathogenic mutations in the 12 genes associated mostly with European ancestry. They found that:

For AA women overall

• Pathogenic mutations previously identified in White women are also highly predictive for developing breast cancer in Black women.
• Among the 23 genes tested in this study, pathogenic mutations were identified in 8% of AA women who had breast cancer and 2% who did not.
• Mutations in BRCA1, BRCA2, and PALB2 were linked with high risks of developing breast cancer.
• Mutations in the genes CHEK2, ERCC3, and RECQL were linked with moderate risks for developing cancer.

This study estimates that Black women with mutations in the gene PALB2 have a 58% lifetime risk of developing breast cancer (by age 85 years). The lifetime risk of breast cancer for women with BRCA2, CHEK2, and ATM are 48%, 30%, and 21% respectively.  

For AA women with ER- breast cancers (including triple-negative breast cancers)

• Frequency of pathogenic mutations was especially high (10%) in AA women with ER- breast cancer.
• Mutations in the genes BRCA1, BRCA2, PALB2, and RAD51D were linked with a high risk of ER- breast cancer.
• Mutations in genes BRCA1, PALB2,and RAD51D were more strongly associated with ER- than ER+ breast cancer.

For AA women with ER+ breast cancers

• Mutations in genes CHEK2, ATM, ERCC3, and FANCC were only associated with ER+ breast cancers, but only at a moderate risk level.
• Mutations in genes BRCA1 and PALB2 were associated with ER+ breast cancer but not as strongly as they were with ER- breast cancers.

The lead author of the published study was Julie Palmer, ScD, from Trustees of Boston University and an American Cancer Society (ACS) research grantee. Some of the many other contributors included former ACS grantees Jeffrey N. Weitzel, and Fergus Couch, PhD, (senior author), and former ACS epidemiology researcher, Mia Gaudet, PhD.

In a follow-up study, members members of the CARRIERS consortium looked for racial differences in the prevalence of pathogenic mutations in breast cancer predisposition genes between US Black and White women.

They found that the prevalence of pathogenic mutations in 3 genes— BRCA2, CHEK2, and PALB2—was higher in Black women, but they noted that the differences were small. The authors concluded that there was not sufficient evidence to make changes to currently available genetic testing guidelines based on race alone. This is because the current guidelines already account for the fact that Black women are diagnosed with breast cancer at a younger age than White women, more often have triple-negative breast cancer, and more frequently have a family history of ovarian cancer.

This second study used CPS-II as part of the reviewed data and its authors again included former grantees Couch and Palmer.

Why Does It Matter?

There have been some misconceptions that breast cancer genetic counseling and testing is not applicable to Black women.The first study’s findings demonstrate that learning whether a woman has mutations in certain cancer predisposition genes is, in fact, highly predictive of the development of breast cancer in Black women.

In the second study, the authors’ note that Black women are less likely to undergo breast cancer genetic testing than White women, largely owing to differences in physician recommendations or access to care. The CARRIERS’ authors advise health care professionals make continued efforts to reduce barriers for genetic testing for Black women and ensure equal access and uptake of genetic testing to minimize disparities in care and outcomes based on race.