Basal-like breast cancers

Cluster analysis of data derived from complementary DNA microarrays has demonstrated that breast cancers are divisible into at least 5 molecular subclasses. Basal-like breast cancers represent 1 of these subclasses. These tumors constitute approximately 20% of breast cancers, show overexpression of genes and proteins characteristic of the normal myoepithelial cell, and have been associated with a worse overall and disease-free survival as compared with most of the other subclasses. In this article, we present a case of basal-like breast cancer and summarize the rapidly expanding literature on the most salient clinicopathologic attributes of breast cancers classified as "basal-like" by gene expression profiling and/or immunohistochemical criteria.