The Distinctive Nature of HER2-Positive Breast Cancers

Breast cancer is not a single disease but a group of several important tumor subtypes, each with a different natural history and each requiring a different treatment. Overexpression of HER2 (which derives its name from human epidermal growth factor receptor 2) defines one of these unique subtypes. The HER2/neu gene is a member of a family of genes encoding transmembrane receptors for growth factors, including the epidermal growth factor receptor (EGFR), HER2, HER3, and HER4. The intracellular domain of HER2 has tyrosine kinase activity that regulates important aspects of the physiology, growth, and differentiation of cells.1,2 Extracellular domains of . . .