MONDAY, Oct. 31 (HealthDay News) -- Women testing negative for their family-specific BRCA1 or BRCA2 mutation (noncarriers) do not have an increased risk of breast cancer, according to a study published online Oct. 31 in the Journal of Clinical Oncology.
Allison W. Kurian, M.D., from the Stanford University School of Medicine in California, and colleagues estimated breast cancer risks for women who were not carriers of the BRCA1 or BRCA2 mutation. Women with breast cancer from 3,047 families in the Breast Cancer Family Registry and their female first degree relatives (FDRs) were tested for BRCA1 and BRCA2 mutations.
The investigators identified 160 families with BRCA1 and 132 with BRCA2 mutations. Noncarriers of identified mutations had no evidence of increased breast cancer risk compared with FDRs from families without BRCA1 or BRCA2 mutations (relative risk, 0.39; 95 percent confidence interval, 0.04 to 3.81). There was a strong residual breast cancer association within families, with 3.4 percent of women without BRCA1 or BRCA2 mutations accounting for approximately one third of breast cancer cases.
"We found no evidence for an increase in breast cancer risk for noncarriers of a family-specific BRCA1 or BRCA2 mutation in this study of 3,047 population-based families recruited from three countries," the authors write.