Epidermal growth factor receptor in human breast cancer: correlation with cytosolic and nuclear ER receptors and with biological and histological tumor characteristics.

Epidermal growth factor receptor (EGFr) and cytosolic (cER) and nuclear (nER) estradiol receptors were quantified in 220 primary breast cancers. The EGFr was significantly more frequent (chi 2 = 5.9; P less than 0.025) and its concentration was significantly higher (P less than 0.001) among ER- tumors than in ER+ tumors. There was a significantly greater proportion (chi 2 = 6.4; P less than 0.05) of node involvement in EGFr+/ER+ tumors than in EFGr-/ER+. Increases in the proportion of EGFr+ in ER- tumors are parallel to Scarff-Bloom scores (chi 2 = 6.1; P less than 0.05) and there is a significant trend (Spearman rs = 0.25; P less than 0.05) towards increased EGFr concentrations with histologic dedifferentiation. In ER+ tumors the median concentrations of EGFr in the different age groups show a linear correlation (LCC = 0.89; P less than 0.05) and follow a parallel profile with the medians of nER. These findings support the hypothesis that EGFr is a bad prognosis factor and suggest that EGFr expression and concentration in ER+ tumors might be considered an estrogenic action mediated through the binding of ER to their nuclear acceptors.