Pharmacotherapy of triple-negative breast cancer.

The term 'triple-negative breast cancer' defines tumors that do not express estrogen receptors, progesterone receptors or Her2 on immunohistochemical analysis. This subgroup accounts for 15% of all types of breast cancer. Histologically, triple-negative breast cancers are poorly differentiated and are characterized by an aggressive clinical history. A significant overlap exists in biological and clinical characteristics of basal-like breast cancer and triple-negative breast cancer. Treatment options are limited, as these tumors lack a therapeutic target and are naturally resistant to existing targeted therapies, i.e., endocrine treatment and trastuzumab. As there are no specific treatment guidelines for this subgroup, triple-negative breast cancers are managed with standard treatment; however, local and systemic relapse rates are high due to the adverse biology of the disease. Triple-negative breast cancer has many histological and genetic similarities with BRCA-1-associated breast cancer, suggesting a common pathogenesis and the potential use of common chemotherapeutics in both cancers. This review discusses current and future treatment options in the light of the new insights in major proliferative pathways active in the pathogenesis of triple-negative breast cancer.