Of 1111 primary BRCA screens with confirmed HER2 status only 4/161 (2.5%) of women with HER2 amplification had a BRCA1 mutation identified and 5/161 (3.1%) a BRCA2 mutation.
For this purpose, we analysed primary mutation screens on women with breast cancer with unequivocal HER2 amplification and assessed the proportion of BRCA1 and BRCA2 breast cancers that were HER2+ comparing this with the existing literature.
Although BRCA1-associated and sporadic tumors were equally likely (19% versus 22%) to exhibit HER-2/neu amplification [defined as a ratio of HER-2/neu copies to chromosome 17 centromere (CEP17) copies > or = 2], 6 (15%) of the sporadic tumors were highly amplified (defined as a ratio greater-than-or-equal 5) versus none of the BRCA1-associated tumors (P = 0.048).
HER-2/neu (c-erbB-2) gene amplification based on Southern blotting or immunohistochemistry has been shown to be predictive of poor outcome in breast cancer occurring in women over 40, but there is little data on the role of HER-2/neu in young women with breast cancer, many of whom may have inherited BRCA1 or other predisposing genes.