A high percentage of African American women with breast cancer who were evaluated at a university cancer-risk clinic were found to carry inherited genetic mutations that increase their risk for breast cancer. Genetic testing could help to protect such patients and their relatives. A study reflecting these findings was presented at the 2013 annual meeting of the American Society of Clinical Oncology in early June in Chicago, Illinois.

The research findings suggest that inherited mutations may be more common than anticipated in this understudied group. The study may partially explain why African Americans more often develop early onset and “triple-negative” breast cancer.

The study also demonstrates the potential benefits of increased access to genetic counseling and testing for women with breast cancer and their close relatives. Through these services, family members who are found to share the same genetic risk factor for breast cancer can be offered personalized strategies for early detection and prevention of breast cancer.

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“Our study confirms the importance of screening for mutations in breast cancer susceptibility genes in all African American breast cancer patients diagnosed by age 45, those with a family history of breast or ovarian cancer, or with triple-negative breast cancer before age 60,” said study author Jane Churpek, MD, of the University of Chicago Medicine. “This could identify at-risk family members in time for life-saving interventions and help prevent future cancers for the patients as well.”

This study is the first comprehensive screening among African American women of all 18 known breast cancer susceptibility genes using the new methods of targeted genomic capture and next-generation sequencing. Among the 249 women studied, 56 (22%) had inherited at least one damaging mutation that increased their risk of breast cancer. A mutation in BRCA1 occurred in 26 of the patients; 20 patients had a BRCA2 mutation; 12 had mutations in the genes for CHEK2, PALB2, ATM, and PTEN; and two had inherited mutations in two different genes.

Patients most likely to carry a mutation were those diagnosed with a second primary tumor, and 49% of those women carried an inherited breast cancer-associated gene mutation. Other groups highly likely to carry inherited mutations included those with a close relative who had either breast or ovarian cancer (30%), those with triple-negative breast cancer (30%), and those who were diagnosed with breast cancer by age 45 (27%).

The authors caution that the patients in this study are not a typical cross-section of African American women. Two-thirds of them were referred to the cancer-risk clinic for genetic evaluation, often due to a family history of breast cancer. Not all of them, however, had this significant risk factor. No family history of breast or ovarian cancer existed for 40% of the enrolled patients, yet the researchers found damaging mutations in 12% of those patients.