Triple-Negative Breast Cancer

A PUBMED SEARCH OF THE MEDICAL LITERATURE SHOWS THAT THE FIRST mention of "triple-negative" breast cancer was in October 2006; since then, the term has appeared in more than 600 publications.1 This increase reflects the growing recognition of the importance of triple-negative breast cancer (see the Glossary for this and other key terms) by oncologists, pathologists, and geneticists, as well as by the approximately 12 to 17% of women with breast cancer who have triple-negative breast cancer. As a group, patients with triple-negative tumors have a relatively poor outcome and cannot be treated with endocrine therapy or therapies targeted to human epidermal growth factor receptor type 2 (HER2). A close cousin of triple-negative breast cancer is basal-like breast cancer (synonymous terms include "basal-type," "basal-epithelial phenotype," "basal breast cancer," and "basaloid breast cancer"). This molecular subtype of breast cancer is characterized by a gene-expression profile that is similar to that of the basal-myoepithelial layer of the normal breast. 2 Immunohistochemical markers have been used as a surrogate for this profile. The multiplicity of names reflects an underlying uncertainty as to the true nature of this entity. Copyright © 2010 Massachusetts Medical Society.