Germline BRCA1 Mutations and a Basal Epithelial Phenotype in Breast Cancer

A basal epithelial phenotype is found in not more than 15% of all invasive breast cancers. Microarray studies have shown that this phenotype is associated with breast cancers that express neither estrogen receptor (ER) nor erbB-2 (HER2/neu) (i.e., ER/erbB-2-negative tumors). The ER/erbB-2- negative phenotype is also found in breast cancers occurring in BRCA1 mutation carriers (i.e., BRCA1-related breast cancers). We tested the hypothesis that …