A Review of Triple-negative Breast Cancer

Roohi Ismail-Khan, MD; Marilyn M. Bui, MD, PhD

Disclosures

Cancer Control. 2010;17(3):173-176. 

In This Article

Abstract and Introduction

Abstract

Background: An estimated 1 million cases of breast cancer are diagnosed annually worldwide. Of these, more than 170,000 are described as triple-negative. Triple-negative breast cancer (TNBC) is defined by the lack of protein expression of estrogen receptor (ER) and progesterone receptor (PR) and the absence of HER2 protein overexpression. TNBC is a subtype of breast cancer that overlaps with the "basal-like" breast cancer. TNBC has significant clinical implications.
Methods: The epidemiology, diagnosis, clinical course, prognosis, and pathology of this subtype of breast cancer are reviewed. The authors compare the "triple-negative" and "basal-like" definitions of breast cancer. A discussion of both standard and experimental treatments for TNBC is included.
Results: The poor prognosis of high-grade TNBC relates to poor disease-free interval in the adjuvant setting, shortened progression-free survival in the metastatic setting, and the lack of targeted therapy. However, not all TNBCs are associated with a poor prognosis.
Conclusions: Although chemotherapy is the main current treatment of this subtype of breast cancer, new agents such as PARP inhibitors, which show promise in the treatment of TNBC, are currently in clinical trials.

Introduction

Breast cancer is the most common cancer among women in the United States, the second most common cause of cancer death, and the main cause of death in women ages 45 to 55 years. In 2009, approximately 192,370 American women were diagnosed with breast cancer, and an estimated 40,170 women died of the disease.[1] Triple-negative breast cancer (TNBC) accounts for approximately 15% of breast cancers.[2] Although recently in the limelight and frequently discussed, TNBC is not a new type of breast cancer. In fact, the term has recently been coined to describe a subtype of breast cancer that lacks expression of the estrogen receptor (ER) and progesterone receptor (PR) and does not overexpress human epidermal growth factor 2 receptor (HER2) protein. TNBC is an important area of research for both researchers and clinicians alike because (1) TNBC is a poor prognostic factor for disease-free and overall survival, (2) no effective specific targeted therapy is readily available for TNBC, (3) there is a clustering of TNBC cases in premenopausal women and in women of African descent, and (4) the overlap of BRCA1-associated breast cancers with the TNBC phenotype is significant.

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