Old and new concepts in histopathological characterization of familial breast cancer.

BRCA1- and BRCA2-deficient cells display genomic instability due to impaired DNA repair and may subsequently be predisposed to malignant transformation. Cancers arising in BRCA1 gene mutation carriers differ substantially from sporadic breast cancers of age-matched controls in their histopathological appearance. BRCA1-related breast cancers have been morphologically associated with poorly differentiated and medullary types, exhibiting triple negativity and 'basal phenotype'. There are different types of mutations listed in Breast Cancer Information Core professional databases and most of them are small insertions or deletions. Moreover, the search for more pathological alterations has led to identification of missense mutations, intronic variant sequences and unclassified variants, reporting an unclear role in breast cancer susceptibility. We review the latest evidence regarding analysis of various mutations in BRCA1/2 genes and low-risk breast cancer susceptibility genes. Preliminary data from our laboratories indicate that biomarkers for invasiveness may lead to better characterization of familial breast cancers. Multivariate regression analysis has allowed us to select the best combination of markers to predict familial or hereditary breast cancers. We found that a marker signature comprising human epidermal growth factor receptor 2 (HER2) negativity, Na(+)/H(+) exchanger regulatory factor 1 (NHERF1) negativity and BRCA1 positivity (designated 'triple-biomarker' signature) is frequently associated with familial breast cancer and promises to be a reliable test in its molecular characterization.