A new study has found that women who are members of families with BRCA2 mutations but who test negative for the family-specific BRCA2 mutations are still at greater risk for developing breast cancer compared with women in the general population.

Women with certain mutations in their BRCA1 or BRCA2 genes are at increased risk for breast cancer. However, the study suggested that it may not always be true.

"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," Gareth R. Evans from University of Manchester in the United Kingdom, said. "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 said that it is likely that these women inherit genetic factors other than BRCA-related genes that increase their breast cancer risk. About 77 single nucleotide polymorphisms are linked to breast cancer risk.

He said that identification of additional SNPs is necessary to understand why some of the BRCA-negative women from BRCA families are at higher risk.

The authors noted that specialists should use caution when stating that a woman's breast cancer risk is the same as that of the general population following a negative test, because it may not be true for some women who come from BRCA2 families with a strong family history.

The study is published in journal Cancer Epidemiology, Biomarkers and Prevention.