Mesenchymal Subtype of Triple-Negative Breast Cancer: A Review of Specific Features

Abstract

Triple-negative breast cancer (TNBC) is characterized by high invasiveness, high metastatic potential, proneness to relapse, and poor prognosis. Currently, four subtypes in the classification of triple-negative breast cancer (TNBC) are distinguished, which differ from each other in morphological manifestations, molecular genetic features, survival rates, prognosis parameters, and tumor resistance to therapy. A special place in this breast tumors group is occupied by the mesenchymal subtype, the frequency percentage of which varies from 7% to 28%, according to different data. The mesenchymal subtype of TNBC (M-TNBC) is characterized by the expression of molecular markers related to the epithelial-mesenchymal transition (EMT) program and cancer stem cells. M-TNBC has a highly aggressive behavior and worse prognosis due to its invasive and stem-like features, which correlate with metastatic dissemination and resistance to therapies. This review discusses the current knowledge regarding the mesenchymal TNBC subtype and its response to conventional therapeutic strategies. The complex approach to finding effective treatment options to restore immunocompetence in mesenchymal breast cancer patients is the final goal for further extended studies.

Keywords

• triple-negative breast cancer
• epithelial-mesenchymal transition
• molecular markers