Prognostic and predictive values of HER1 and HER2 overexpression in breast cancer *
Overexpression of the epidermal growth factor receptors, HER1 and HER2, has been detected in 20-40% of primary breast cancers. It has been suggested that patients with breast cancer overexpressing these receptors have a poor prognosis. Their overexpression has been also suggested to be a predictive factor for the response to therapy. HER1- and HER2-overexpressing breast cancers have been shown to be resistant to an antiestrogen, tamoxifen. HER2-overexpressing breast cancer has been reported to be sensitive to anthracycline-containing regimens and taxanes. Recently a selective HER1 tyrosine kinase inhibitor, ZD1839, and a humanized anti-HER2 monoclonal antibody, trastuzumab, have been developed and introduced into clinics. These findings prompted us to investigate the prognostic and predictive values of HER1 and HER2 overexpression in breast cancer. < Patients and Methods > A total of 420 patients underwent radical operation at the Department of Breast and Thyroid Surgery, Kawasaki Medical School between 1991 and 1999. From among these, 52 patients with recurrent disease in whom response and outcome to therapies were evident were selected as the subjects of this study. Paraffin-embedded primary breast cancer specimens of these patients were immunohistochemically examined for HER2, p53 and Ki67 expression. The HER1 expression was examined by a ligand-binding assay. Correlation between the expression of these biological markers and the survival or response to therapies was investigated using uni- and multivariate analyses.
