Expression of epidermal growth factor receptor in human breast carcinoma and its correlation with morphological and biological features of tumour aggressiveness.

: A series of 54 patients presenting with primary breast cancer were investigated for tumour expression of epidermal growth factor receptor (EGFR) by the indirect three-step immunoperoxidase technique which used the monoclonal antibody EGFR1. The percentage of malignant cells positive for EGFR was determined and scored on a four-point (0-3) scale in each case. EGFR was demonstrated in 35 (64.8%) tumours. EGFR expression did not correlate (p greater than 0.05) with growth fraction immunohistochemically visualized by means of the monoclonal antibody Ki-67, tumour size, axillary lymph node status and malignancy grade. In contrast, a significant inverse relationship (p less than 0.05) was found between EGFR and estrogen receptor (ER) patterns. Expression of EGFR per se does not appear to be relevant to the biological behaviour of breast cancer as revealed through an evaluation of proliferative activity, pathological stage and histological differentiation. Recognition that EGFR is negatively related to ER supports the present evidence that the control of malignant cell growth and differentiation depends on complex regulatory mechanisms in which several extracellular messenger molecules, including hormones and peptide growth factors together with their specific cellular receptors, are involved and inextricably interwoven.