Prognostic value of epidermal growth factor receptor in a series of 303 breast cancers.

125I-EGF (epidermal growth factor) binding assay was used in tumoral specimens concerning 303 clinical T1-T2, N0-N1 breast carcinoma diagnosed between May 1987 and October 1989. Binding assay for epidermal growth factor receptor (EGFR) was performed using single saturating concentration of 125I-EGF incubated with membrane preparations in the presence or absence of unlabelled EGF. A median value of 3 fmol EGF binding capacity per mg of membrane was obtained and then selected as the threshold value to define positive and negative EGFR tumour samples. According to this definition, 50.8% of the samples were EGFR positive. We noted an inverse relationship between the expression of EGFR and that of oestrogen receptor, and a decreased EGFR expression with tumour differentiation. With a rather short median follow-up (16 months), the multivariate analysis shows that progesterone receptor appears as the only powerful predictor of disease-free survival (P = 0.002), taking into account that 70% of the patients received an adjuvant medical treatment.