neu(c-erbB-2/HER2) and the epidermal growth factor receptor (EGFR) in breast cancer.

One hundred and eighty thousand new cases of invasive breast cancer were diagnosed in 1992 within the United States. This disease affects approximately 1 out of 8 women in the US. Chemotherapy and/or hormonal therapy have shown some improved disease-free and/or overall survival rates. Unfortunately, this type of therapy is not directed specifically to the malignant cells, and systemic toxicities are observed. In order to develop site-specific treatment, the biology of the disease must be understood such that certain genes or their products which are involved in the pathogenesis of the disease can be targeted. Two structurally related tyrosine kinase growth factors, the epidermal growth factor receptor (EGFR) and c-erbB-2 (neu) have been identified in human breast cancer tissue and, in many instances, may function as oncogenes. The clinical data related to these two growth factor receptors as prognostic factors for the disease have been critically evaluated. Several problems with the critical studies were identified, and solutions were proposed to clarify the conflicting results reported in the studies which have attempted to examine whether c-erbB-2 (neu), in particular, is a prognostic indicator for breast cancer. In addition, data related to the structure of, ligands for and interaction between the proteins have been reviewed and presented with respect to their role in breast cancer development. A more thorough understanding of the genetic changes which contribute to the development of breast cancer will lead to more specific and less toxic treatment for this disease.