DIFFERENTIAL EXPRESSION OF ESTROGEN, PROGESTERONE, AND EPIDERMAL GROWTH-FACTOR RECEPTORS IN NORMAL, BENIGN, AND MALIGNANT HUMAN BREAST TISSUES USING DUAL STAINING IMMUNOHISTOCHEMISTRY

Distribution of estrogen (ER), progesterone (PR) receptors, and epider mal growth factor (EGF) receptors was assayed by dual staining immunoh istochemistry on 28 selected cytosolic ER-positive breast carcinomas a nd 22 nonmalignant breast tissues. ER-positive tumor cells were detect ed in 26 (93%) and EGF receptor positive tumor cells were detected in 7 (25%) carcinomas. In five tumors both ER and EGF receptors were dete cted but localized in distinct tumor cells. Only in one case of ductal carcinoma in situ coexpression was observed in a subset of tumor cell s. In contrast, simultaneous expression of ER/PR and EGF receptors was observed in nonneoplastic ductal remnants in the majority of the carc inomas and the fibroadenomas. In addition, double-positive cells were occasionally detected in luminal epithelial cells of normal breast tis sue and mastopathies. This study shows that ER/PR and EGF receptors in breast tumor cells are inversely related at the single cell level How ever, demonstration of ER/PR and EGF receptors in individual normal lu minal cells shows that expression is not mutually exclusive.