The Risk of Breast Cancer in BRCA1 and BRCA2 Mutation Carriers without a First-Degree Relative with Breast Cancer.

Metcalfe KA1,2, Lubinski J3, Gronwald J3, Huzarski T3, McCuaig J4, Lynch HT5, Karlan B6, Foulkes WD7, Singer CF8, Neuhausen SL9, Senter L10, Eisen A11, Sun P2, Narod SA10; Hereditary Breast Cancer Clinical Study Group.

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Abstract

The objective of this study was to estimate the lifetime risk of breast cancer in women with a BRCA1 or BRCA2 mutation with and without at least one first-degree relative with breast cancer. A total of 2835 women with a BRCA1 or BRCA2 mutation were followed. Age- and gene-specific breast cancer rates were calculated. The relative risks of breast cancer for subjects with a family history of breast cancer, compared to no family history were calculated. The mean age at baseline was 41.1 years, and they were followed for a mean of 6.0 years. The estimated penetrance of breast cancer to age 80 years was 60.8% for BRCA1 and 63.1% for BRCA2. For all BRCA carriers, the penetrance of breast cancer to age 80 for those with no first-degree relative with breast cancer was 60.4%, and was 63.3% for those with at least one first-degree relative with breast cancer. The risk of breast cancer for BRCA carriers with no first-degree relative with breast cancer is substantial, and as a result, clinical management for these women should be the same as those for women with an affected relative.