Molecular Phenotype, Multigene Assays, and the Locoregional Management of Breast Cancer

Molecular profiling has revealed that breast cancer is not a single disease entity, but rather a class of heterogeneous subtypes, each with its own inherent biology and natural history. As a result, different treatment approaches have been optimized for the various subtypes and, in turn, the ability to identify subtypes has become a critical element in the management of breast cancer. Comprehensive transcriptional profiling studies have revealed at least 4 principal subtypes that, in practice, are often distinguished by immunohistochemical staining of the estrogen receptor (ER), progesterone receptor (PR), and HER2, along with a determination of histologic grade or Ki-67 staining: luminal A (ER+/HER2−/grade 1 or 2), luminal B (ER+/HER2−/grade 3), HER2 enriched (any HER2+ tumor), and basal like (ER−/PR−/HER2−).
Source: Seminars in Radiation Oncology - Category: Cancer & Oncology Authors: Source Type: research