Angelina Jolie made major headlines earlier this year when she revealed that she'd tested positive for a faulty BRCA1 gene (which puts your odds of breast cancer at about 87 percent)—and had decided to get a double mastectomy because of it. Women with a family history of breast or ovarian cancer (such as Jolie) sometimes undergo genetic testing so that, if they find out they have a mutated BRCA1 or BRCA2 gene, they can start fighting cancer before they get it. The thinking has always been that if a womandidn't have the genetic mutation, her odds of getting breast cancer were about that of anyone in the general population, according to the National Cancer Institute.
But now, new research reveals that women who test negative for the mutation may be at a higher risk, too: Women who have family members with mutated BRCA2 genes may have an increased risk of breast cancer, even if they do not exhibit the genetic mutation themselves, according to a new study published in the journal Cancer Epidemiology, Biomarkers & Prevention.
For the study, researchers from the University of Manchester in the U.K. looked at 807 families that had at least one member with a mutated BRCA1 or BRCA2 gene. Within that pool of participants, researchers identified 49 women who tested negative for the mutation but still went on to develop breast cancer.
"We found that women who test negative for family-specific BRCA2 mutations have more than four times the risk for developing breast cancer than the general population," says Gareth R. Evans, M.D., honorary professor of medical genetics and cancer epidemiology at the Manchester Academic Health Science Center at the University of Manchester. "It is likely that these women inherit genetic factors other than BRCA-related genes that increase their breast cancer risk."