A Procedure for the Simultaneous Assay of Estrogen, Progesterone and Epidermal Growth Factor Receptors in the Same Tissue Specimen.

Estrogen (ER) and progesterone (PR) receptor assay in breast cancer is clinically useful in selecting patients for endocrine therapy and as a prognostic indicator(1-5). Recently, evidence has been reported suggesting that the expression of epidermal growth factor receptor (EGFR) in breast cancer cells represents an additional prognostic parameter (6-8). Specifically, a subset of tumors which are EGFR positive and ER negative has been described, suggesting the presence of hormone independent breast tumors whose growth is primarily regulated by EGF (9-11). Therefore the simultaneous determination of both EGFR and steroid receptors may be of considerable importance. This may often be difficult due to the small amount of tissue available. In this report, we describe a simple procedure to analyze ER, PR and EGFR simultaneously in the same specimen of tissue.