Immunocytochemical determination of epidermal growth factor receptor with monoclonal EGFR1 antibody in primary breast cancer patients.

Epidermal growth factor (EGF) has been shown to be important in regulating the growth of breast cancer cells in vivo because of its mitogenic action on some breast cancer cell lines in vitro. Immunocytochemical analysis of EGF receptor (EGFr) was carried out on frozen sections in 134 primary breast cancer patients. Overall 68 of 134 (51%) of the tumors were EGFr positive. There was no correlation between EGFr positivity and menopausal status. Regarding the histopathological features, no significant correlations were observed between EGFr expression and tumor size, grading and lymph nodes status. Estrogen (ER) and progesterone (PgR) receptors were detected by an immunocytochemical assay and an equal distribution of EGFr was found regarding steroid hormonal receptors expression. Finally, there was only a positive trend between the proliferative activity of the tumors, as measured by Ki-67 antibody, and the amount of EGFr. Our results suggest the presence of a subclass of breast tumors, characterized by the absence of ER and/or PgR and the presence of EGFr, whose growth appears to be mediated by autocrine growth factors rather than by steroid hormones. The overall picture is that of an independent relationship between EGFr expression and the known prognostic factors in breast cancer.