Identification of Putative Nonfunctional Steroid Receptors in Breast and Endometrial Cancer

Abstract

Breast and endometrial carcinomas remain major oncologic problems. Both types of cancer are considered to be responsive to endocrine therapy. This is particularly true in the case of breast cancer whether one considers ablative or additive therapy (Ingle 1984; Ingle et al. 1986). However, tumor responses to steroid therapy vary (Fig. 1). In general, for breast carcinoma, the tumors of about one-half of estrogen receptor (ER)-positive breast cancer patients as assessed by the dextran-coated charcoal assay (DCC assay), respond and one-half do not respond (Edwards et al. 1979; McGuire 1980). Progesterone receptor (PR) status is usually assessed in cases of endometrial cancer, most of which are diagnosed in early clinical stages. Progestational agents are the treatment of choice in cases of advanced disease, yet only 11%–40% of unselected patients respond (Wait 1973); Kohorn 1976; Piver 1980; Podratz 1985). Recent results from a large study indicate that tumors which contain high levels of PR by the DCC assay show a positive response 60% of the time (Ehrlich 1988).