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Estrogen receptor assays were performed on tumor specimens from 6 male patients with documented breast cancer. Five out of six (83%) males had positive ER assays with values ranging from 23-384 femtomoles per mg cytosol protein. A review of the literature showed that 32 out of 38 patients (84%) reported were positive for estrogen receptor. Four out of five ER positive males responded to orchiectomy. Estrogen receptors are present in a high percentage of males with breast cancer and may predict response to treatment, similar to female breast cancer.

The dextran-coated charcoal assay method of McGuire and DeLaGarza is a well-known method for quantitation of oestrogen receptors in breast tumour tissues. Castañeda and Liao reported that the solid-phase antisteroid antibodies are superior to dextran-coated charcoal for quantitating the receptor bound steroids. In this report we compare the results obtained using both methods to quantitate oestrogen receptors and determine the affinity for steroid binding in seven human breast tumours and the uteri of rat and calf.

An immunofluorescent method has been developed for localizing estrogen receptors (ER) in frozen sections of human breast cancer biopsies which utilizes the biochemically well-characterized antibodies to the cytoplasmic ER of human breast cancer produced in rabbits. Frozen sections of sixteen breast cancer biopsies, in which the receptor content has been quantified using dextran-coated charcoal assay (DCC technique), were used to study the localization of ER. Two aspects of ER detection, namely "estrogen-binding" and ability to react with the homologous antibodies, have been analyzed and the results compared with those of DCC technique. Fluorescent labelled estrogen method (F.E2) of Pertschuk was utilized to detect the distribution of estrogen binding proteins and the indirect immunofluorescent (IM-AR) method using anti-receptor antibodies to assess the antigenic sites of the receptor protein. In addition to the comparison of the results of three techniques, DCC, IM-AR and F.E2, for ER detection, a procedure for processing the frozen sections, which enables the study of estrogen binding characteristic as well as the antigenic reactivity of the receptor molecules, is described.

Rabbit antibodies to cytoplasmic estrogen receptors (ER) of human breast carcinoma were utilized for investigating steroid-triggered in-vitro translocation of cytoplasmic ER to the nuclear compartment of the estrogen target cells. The immunofluorescent method (IF) previously described (S Raam et al., Eur J Cancer Clin Oncol 18: 1-12, 1982) was employed for immunohistochemical localization of ER. Four cases of normal endometrium, two cancers of the endometrium, and MCF-7 human breast cancer cells were maintained in a steroid free medium and exposed at 37 degrees C for two hours to growth medium alone (control) or to 2.5, 25 or 250 nanomoles of estradiol (E2), diethylstilbestrol (DES), or monohydroxytamoxifen (OH-TX). At the end of the incubation period the cells were processed for intracellular localization of ER. Complete traslocation of IF from the cytoplasm to the nuclear compartment was evident in all normal endometrial cells exposed to E2, DES or OH-TX for two hours. While cells from the endometrial cancer 'S', like the normal cells, translocated IF to the nucleus, cells of another cancer ('KLE') failed to translocate when exposed to E2 or OH-TX. Partial translocation was evident in 'KLE' cells exposed to DES. In MCF-7 cells grown in the absence of E2, IF was exclusively cytoplasmic. When these cells were exposed to the hormones, 50% showed a complete transfer of IF to the nucleus; in 40% a delayed response was evident; 10% failed to translocate. The results revealed the suitability of anti-ER antibodies for investigating the intracellular dynamics of ER in target cells responding to estrogens or antiestrogens.

Eighty-eight patients with advanced breast cancer were retrospectively reviewed to compare estrogen receptor (ER) data with response to cytotoxic chemotherapy. All assays were done in a single laboratory. All patients were cared for at a single institution. Thirty-four patients were treated with chemotherapy, 30 of whom were evaluable for response by criteria of the Eastern Cooperative Oncology Group (ECOG). Of 16 ER-positive patients, 12 (75%) responded; of 14 ER-negative patients, six (43%) responded (P < 0.05). The two groups did not differ significantly in chemotherapy received, menopausal status, site of predominant disease, stage at diagnosis, or disease-free interval. Response to cytotoxic chemotherapy does not appear to correlate with ER status.