Triple-negative breast cancer accounts for 15 percent of breast cancer in the Caucasian population and 35 percent in the African-American population. (For Spectrum Health Beat)

More genes associated with an increased risk of triple-negative breast cancer have been identified by researchers.

Until now, only mutations in the BRCA1 gene have been linked with this type of breast cancer.

“Triple-negative breast cancer is an aggressive type of cancer that cannot be treated using targeted therapies,” study leader Fergus Couch, a geneticist at the Mayo Clinic, explained in a clinic news release.

“It accounts for 15 percent of breast cancer in the Caucasian population and 35 percent in the African-American population. It is also associated with a high risk of recurrence and a poor five-year survival rate. Our findings provide the basis for better risk management,” Couch said.

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Our Take

Although breast cancer is far too common, breast cancer survival is improving due to more advanced treatments and early screening for women at high risk.

Do you know your risk, and do you have a plan for when you should be screened? Diana Bitner, MD, urges women to know their risks, live a lifestyle that decreases risk, and take checkups seriously.

The genetics of breast cancer:

  • Ten percent of breast cancer is associated with family history.
  • The risk of getting breast cancer increases two times if one first-degree relative has or had breast cancer.
  • The risk of getting breast cancer increases three times if two first-degree relatives has or had breast cancer.

In addition, 50 percent of breast cancer diagnoses are associated with known risk factors.

The researchers conducted genetic tests on nearly 11,000 patients with triple-negative breast cancer and found that mutations in the BARD1, BRCA1, BRCA2, PALB2 and RAD51D genes were associated with a high risk for triple-negative breast cancer and a greater than 20 percent lifetime risk of any type of breast cancer among whites. Similar findings were made among blacks.

The team also found that mutations in the BRIP1 and RAD51C genes were associated with a more moderate risk of triple-negative breast cancer.

The findings were published in the Journal of the National Cancer Institute.

“This study is the first to establish which genes are associated with high lifetime risks of triple-negative breast cancer,” Couch said. “While previous studies have found genetic variants in BARD1, BRIP1, PALB2 and RAD51C triple-negative breast cancer patients, the current study shows this in more detail, and identifies new specific and strong associations between the susceptibility genes RAD51D and BARD1, and triple-negative breast cancer risk.”

The findings may result in expanded genetic testing to identify women at risk for triple-negative breast cancer and could lead to improved prevention, Couch added.

U.S. National Comprehensive Cancer Network screening guidelines recommend BRCA testing only for patients with a family history of breast cancer or those who are diagnosed at age 60 or younger, the researchers said.