A study led by Cedars-Sinai found that women who test negative for mutations still face a 25% lifetime risk if they have a family history of cancer.
Women who test negative for BRCA gene mutations may still be at a higher risk of developing breast cancer than the general population, according to a study led by Cedars-Sinai Health Sciences University investigators.
The findings, published in Journal of the American Medical Association Network Open, emphasize the influence of family history on cancer risk. While the average woman has approximately a 13% chance of developing breast cancer during her lifetime, the study found that women who tested negative for a BRCA gene mutation still faced a 25% lifetime risk.
“While most women who undergo genetic testing do not test positive for a cancer-risk-increasing BRCA mutation, they have generally been referred for testing because of strong personal or family cancer history,” says Fahima Dossa, MD, PhD, surgical oncologist at Cedars-Sinai Cancer and lead author of the study, in a release. “Future cancer risk for these women has not been well studied, and our findings are the first to calculate that risk so that we can better guide all women who undergo BRCA testing.”
Impact of Variants and Family History
The research team analyzed the health records of nearly 16,000 women who underwent BRCA testing in Ontario, Canada, from 2007 to 2016. The data showed that lifetime risk for patients with a variant of unknown significance was 30%.
Family history also significantly impacted the risk levels for those who tested positive for a BRCA mutation. Among these patients, breast cancer risk ranged from 56% to 86%, depending on the number of immediate family members who had breast or ovarian cancer.
“Based on these findings, a physician might recommend more frequent mammograms or breast magnetic resonance imaging (MRI) to a BRCA-positive patient in their 50s or 60s with no family history of breast cancer, but suggest preventive mastectomy as an option for a young BRCA patient with several cases of breast cancer in the family,” says Dossa in a release.
Clinical Implications for Genetic Counseling
The study indicates that the only participants with the same breast cancer risk as the general population were those who had a known BRCA mutation in the family, were tested for that specific mutation, and received a negative result.
“This study is a reminder to patients about the importance of having discussions with their doctors about genetic test results,” says Dossa in a release. “We finally have some data to help inform those conversations.”
In July, the organization opened the Cedars-Sinai Cayton BRCA Center to provide screening, guidance, and treatment to patients with BRCA mutations.
“Our leading-edge research supports our efforts to care for and improve outcomes for these patients,” says Robert Figlin, MD, interim director of Cedars-Sinai Cancer, in a release. “Connecting science with cancer care is at the heart of what we do.”
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