A new study has discovered the genes associated with risk of an aggressive breast cancer known as triple-negative breast cancer, which will help provide better risk management for the disease.
Triple-negative breast cancer is an aggressive breast cancer which cannot be treated using the most common therapies and is associated with a high risk of recurrence, as well as a five-year survival rate.
By using germline genetic testing, it can identify women at increased risk of breast cancer by evaluating if there are any genetic changes, often inherited from a parent, that increase the risk of certain cancers.
The challenges when identifying the aggressive breast cancer
There has been difficulty identifying women who are at an increased risk of triple-negative breast cancer because only inherited mutations in BRCA1 have been linked to this subtype of breast cancer.
Researchers performed genetic testing on over 10,000 patients with triple-negative breast cancer from two studies. For 8753 of the patients, 21 genes were tested, while the remaining 2148 patients, 17 genes were tested.
Within the tested genes, researchers found that alternations in BARD1, BRCA1, BRCA2, PALB2, and RAD51D genes were associated with a high risk for triple-negative breast cancer and greater than 20% lifetime risk for overall breast cancer among Caucasian and similar amongst African Americans.
Additionally, mutations in BRIP1 and RAD51C were linked to more moderate risks of triple-negative disease.
Leading to better prevention strategies
This study is the first to establish which genes are associated with high lifetime risks of triple-negative breast cancer. Previous studies have found genetic variants in BARD1, BRIP1, PALB2, and RAD51C more frequently in triple-negative breast cancer patients than in those with other breast cancer subtypes.
The current study, published in the Journal of the National Cancer Institute, manages to show this in more detail and identifies a new specific and strong association between the RAD51D gene and risk of triple-negative breast cancer.
These new findings will now enable expanded genetic testing to identify women at risk of this disease, potentially leading to better prevention strategies.
What does this mean for the current test?
The new finding also suggests potential revisions to the National Comprehensive Cancer Network guidelines, which currently recommends that the BRCA1/2 testing should only be given to a patient has a family history of breast cancer or someone who is diagnosed at age 60 or younger.
With a better understanding of gene-specific risks for triple-negative breast cancer from the study, it will be possible to establish guidelines for testing of other susceptibility genes; and women with genetic changes these genes should be able to receive better risk assessment.
One of the authors of the study, Fergus J. Couch, PhD, concluded: “The results from our study showing that multiple genes cause increased risk of triple-negative breast cancer should help in the clinical management of women found to have inherited mutations in these genes.”