Molecular Prognostic and Predictive Markers in Triple - Negative Breast Cancer

Triple-negative breast cancer (TNBC) is defined as a molecular subtype of breast cancer that lacks expression of hormone receptors (oestrogen and progesterone receptor) and HER2/neu/ErbB2 protein. It accounts for 15–20% of all invasive breast cancers. The occurrence of TNBC is often associated with younger age at the time of diagnosis and pre-menopausal status, early onset of menarche, higher body mass index (BMI) in the pre-menopausal period, race and ethnicity (African, Hispanic) and the presence of germline mutation in the BRCA1/2 genes or somatic mutation in the TP53 or PTEN genes. TNBCs are specific in its aggressive biological behaviour, shorter interval to disease progression and more frequent relapse within five years (19 to 40 months). The most of TNBCs are represented by high-grade invasive carcinomas of no special type (NST) with high proliferation index measured by Ki-67 nuclear expression, followed by metaplastic carcinomas, secretory carcinomas, and adenoid cystic carcinomas. Genetical and morphological heterogeneity inside TNBC is responsible for the higher frequency of primary and secondary resistance to systemic therapy. The scope of this chapter is to summarise the potential therapeutic agents involved in regulation of cell proliferation, migration, angiogenesis, apoptosis, gene expression and DNA damage or immune response. The insight into this issue is essential for the setting of the optimal chemotherapy regimen and targeted therapeutic strategy.