What is the biological, prognostic, and therapeutic role of the EGF receptor in human breast cancer?

The epidermal growth factor receptor (EGFR) is expressed in benign and malignant breast epithelium. The EGFR, when mutated or over-expressed in the presence of its ligand, is transforming in other tissues or cell types. It is therefore of major interest in the pathogenesis of human breast cancer to understand the role of EGFR and its ligands. Additionally, if differential expression is of prognostic value, or if expression provides a therapeutic target, then EGFR may be useful in clinical management and treatment of breast cancer. This issue of Breast Cancer Research and Treatment reviews the basic biology of the EGFR, related members of the EGFR family, the increasing family of ligands for EGFR, and the clinical role in breast cancer, prognosis, and therapy.