Triple Negative Breast Cancer Pathologic Diagnosis and Current Chemotherapy Treatment Options

Abstract

Triple negative breast cancer (TNBC) comprises 12–20 % of all breast cancers and are a heterogeneous group of tumors, both clinically and pathologically. These cancers are characterized by the lack of expression of the hormone receptors estrogen receptor (ER) and progesterone receptor (PR), combined with the lack of either overexpression or amplification of the human epidermal growth factor receptor-2(HER2)gene. Conventional cytotoxic chemotherapy and DNA damaging agents continue to be the mainstay of treatment of this disease in the neoadjuvant, adjuvant, and metastatic setting. The lack of predictive markers in identifying potential targets for the treatment of TNBC has left a gap in directed therapy in these patients. Platinum agents have seen renewed interest in TNBC based on an increasing body of preclinical and clinical data suggesting encouraging activity. However, comparisons between chemotherapy regimens are mostly retrospective in nature and the best agents or drug combinations for TNBC have not been established in prospective randomized trials. Numerous studies have now shown that TNBC has significantly higher pathologic complete response (pCR) rates compared with hormone receptor positive breast cancer when treated with neoadjuvant chemotherapy, and pCR correlates well with better outcomes for these patients. Patients with TNBC account for a larger number of deaths in the setting of metastatic breast cancer. There is no preferred treatment for the first-line metastatic setting. Although individual agents are recommended, given the often aggressive nature of TNBC and the presence of extensive visceral disease, the use of a combination of drugs, rather than a single agent, is often advocated. This review article will outline the pathologic diagnosis of TNBC and the treatment options available to these patients in the neoadjuvant, adjuvant, and metastatic setting, including an assessment of future directions of treatment.