Molecular classification of triple-negative tumors

Excerpt

Triple-negative breast cancers (TNBCs) are among the most clinically challenging because of their poor prognosis and paucity of treatment options. In part through our genomic profiling studies, breast cancer is now appreciated as being composed of multiple diseases. One of these diseases, the basal-like breast cancer (BLBC) subtype, is now known to represent a unique disease entity with a distinct etiology and biology. Over the years, BLBC has become more commonly known as TNBC because the majority of these tumors lack expression of ER, PR and HER2; however, not all TNBC are BLBC, and not all BLBC are TNBC. Recently, we discovered that a significant subset of TNBC is comprised of a new subtype, the claudin-low, which is important because it is biologically distinct from BLBC and has a number of features reminiscent of mammary stem cells [1]. In addition, luminal A, luminal B, and HER2-enriched tumors are also identified within TNBCs in various small proportions, which highlights the complexity of the clinically based classification. …