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

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 highgrade carcinomas, although lowgrade 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 stemlike, luminal androgen receptor, and distinct basallike subtypes that differ substantially from basal like tumors. There are several prognostic makers for TNBC including EGFR and ALDH1, Lysyl OxidaseLike 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.