Triple Negative Breast Cancer: Molecular Classification, Prognostic Markers and Targeted Therapies

Abstract

Context: Triple negative breast cancer (TNBC) is a heterogeneous group of diseases that is negative for esterogen receptor (ER) progesteron receptor (PR) and human epidermal growth factor receptor 2 (HER2). This type of breast cancer is typically high-grade carcinomas, although low-grade tumors occur. The aim of this review is to focus on molecular classification and features, prognostic markers and targeted therapies of triple negative breast cancer. Evidence Acquisition: We searched using electronic databases Pubmed/Medline, Dare, Scopus, Embase, and Cochrane Database of Systematic Reviews with terms of ‘Triple negative breast cancer’, ‘Breast cancer’, ‘Molecular classification’, ‘Immunohistochemical markers’, ‘Molecular features, ‘Targeted therapy’, and ‘Prognostic marker’. Results: It seems that TNBC itself can be subdivided into immunomodulatory, mesenchymal, mesenchymal stem-like, luminal androgen receptor, and distinct basal-like subtypes that differ substantially from basal-like tumors. There are several prognostic makers for TNBC including EGFR and ALDH1, Lysyl Oxidase-Like 2 protein (LOXL2), Synuclein gamma (SNCG), LDHB (Lactate Dehydrogenase B). The antiangiogenic agents, EGFR inhibitors, and PARP inhibitors are new therapeutic Implications and potent factors to targeted therapies of TNBC. Conclusions: Only a few clinical trials are performed on TNBC patients because this disease has a low incidence. Therefore, it seems larger scale clinical trials are needed to be conducted in the future.