(HealthDay News) — Women from BRCA2 families who do not carry a mutation in the BRCA2 breast cancer susceptibility gene still have a nearly five-fold higher risk of developing breast cancer, according to a study published online Nov. 27 in Cancer Epidemiology, Biomarkers & Prevention.
D. Gareth R. Evans, M.B.B.S., M.D., from St. Mary’s Hospital in Manchester, U.K., and colleagues analyzed breast cancer risk in 49 women with breast cancer (out of 807 families with BRCA1 or BRCA2 mutations) who were first-degree relatives of a pathogenic mutation carrier but had tested negative for the family-specific BRCA mutation. Of these, 22 were from families with BRCA1 mutations and 27 were from families with BRCA2 mutations.
The researchers found that there were about twice as many cases of breast cancer in various age ranges than would be expected. Women who tested negative for family-specific BRCA2 mutations had an excess risk of breast cancer (observed to expected ratio, 4.57), while the risk was not substantially higher for family-specific BRCA1 mutations (observed to expected ratio, 1.77).
“Women testing negative in BRCA2 families may have increased risk of breast cancer compared with population levels, particularly with strong breast cancer history in close relatives,” Evans and colleagues conclude.