Role of next generation sequencing technologies for the molecular diagnosis of hereditary breast cancers

Breast cancer (BC) is still the most common tumor in women worldwide. Up to 20-25% of all BCs are of hereditary-familial nature and can be related to germline predisposing-mutations of which the most relevant are present in the high penetrance-genes BRCA1 and BRCA2. These mutations escalate the lifetime risk of BCs and also of other cancers. Thus, their early identification in tumor-prone family members is important to improve the clinical management of patients and their families. In addition, despite their high penetrance, only a small fraction of patients carry BRCA1 or BRCA2 mutations. This suggests that familial BCs may be related to germline mutations in other high-, moderate- and low-penetrance cancer genes. Consequently, the request for laboratory methods able to detect cancer-related pathogenic mutations in a short time and with high accuracy and sensitivity is raised. Recent technological advances in next generation sequencing (NGS) methods development are showing their potential also in this field. Indeed, NGS-based approaches are now currently used for BRCA genes analysis superseding conventional approaches. Moreover, the possibility to simultaneously sequence a panel of target genes is effective to further investigate patients with a personal and/or family history suggestive for an inherited BCs but with no mutations after BRCA molecular test. Implementation of this second-level molecular screening in routine diagnostic workflow will increase the diagnostic sensitivity and improve the management of both patients and their families. In addition, these methodologies could lead to the identification of other BC-related genes, thereby increasing knowledge about hereditary BCs molecular bases.