A negative test result for certain BRCA2 gene mutations--which increase susceptibility to tumor growth--may not be an accurate indicator of a woman's lower risk for breast cancer.
A new study, published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research, has found that even women who have BRCA2 mutations but who test negative for the family-specific BRCA2 mutations still have a greater likelihood of developing breast cancer than women in the general population.
BRCA1 or BRCA2 gene mutations increase a woman's risk for breast cancer, but up until now, scientists believed that if a woman with a family history of BRCA mutations tested negative for these genetic abnormalities, her risk for getting breast cancer was the same as that of a woman without the hereditary gene mutations.
"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," said Dr. Gareth Evans, honorary professor of medical genetics and cancer epidemiology at the Manchester Academic Health Science Center at the University of Manchester in the U.K. "We also found that any increased risk for breast cancer is largely limited to BRCA2 families with strong family history and other genetic factors."
Evans explained that while they may not have the specific BRCA-related mutation, these women likely inherit other genetic factors that increase their breast cancer risk.
When studying 807 BRCA families, researchers identified 49 women who tested negative for the family-specific BRCA mutation but still ended up developing breast cancer. Compared to those in each of the women's age ranges, these women were about twice as likely to develop breast cancer as those from the general population.
The researchers advise physicians to use caution when telling women from BRCA families that they have an average risk of developing breast cancer following a negative test.
- here's the press release