Breast Cancer Prognosis and Management: Role of Gene Expression Profiling

Gene expression profiling has shown that molecular heterogeneity is a hallmark of breast cancer. Authors of a recent review present a comprehensive update of the molecular subtypes of breast cancer and their clinical ramifications. Microarray-based analyses first allowed identification of seven intrinsic subgroups of breast cancer (luminal A, luminal B, basal like, human epidermal growth factor receptor 2 [HER2] enriched, normal breast like, claudin low, and molecular apocrine). These subtypes differ in expression of estrogen receptors (ERs), progesterone receptor (PRs), proliferation-related genes, HER2, and other markers — and each responds differently to chemotherapy and endocrine therapy. Other microarray platforms (e.g., MammaPrint, On…