Biological Subtypes of Triple-Negative Breast Cancer

Triple-negative breast cancers (TNBCs) are defined as tumors that are negative for estrogen, progesterone and HER-2 receptor. At a percentage of 10-20% TNBCs represent a minority in all breast cancers. However, because of the poor prognosis this particular subtype, triple negative disease accounts for a disproportionate number of metastatic cases and breast cancer deaths. Identification of its subtypes is essential for understanding the biological characteristics and clinical behavior of TNBC, as well as for developing personalized treatments. This review will focus on the great progress that has been made in the past few years on identifying new targets in TNBC subtypes and a variety of new treatment options that are on the verge of routine clinical application.