Selection of hormone-responsive advanced breast cancer with a cytoplasmic estrogen receptor assay. Analysis of 100 cases

Immunocytochemical localization of estrogen and progesterone receptors in imprint preparations of breast carcinomas

The role of mammography as an effective means of early detection of breast cancer is well established. Needle localization of occult tumors under mammographic guidance has become the principle method of sampling impalpable breast lesions. As a result, the number of clinically inapparent breast carcinomas sampled has increased rapidly. Under these circumstances, as a result of the size and the nature of these "early carcinomas," it may not be possible to assess the hormone receptor expression of these tumors by conventional biochemical assay and/or immunocytochemical analysis. To determine the usefulness of imprint preparation for detecting hormone receptors, 214 examples of primary, recurrent, and metastatic breast cancers were studied. Immunostaining of imprint preparations with monoclonal antibodies against the estrogen (H222SPy) and progesterone receptors (KD68) showed a high degree of concordance with immunocytochemical assay and biochemical analysis done on frozen tissue of the same tumors. This technique can be done easily and is well suited for tumors that are too small and/or ill defined to permit separate sampling for hormone receptor analysis.

Coexistence of cytoplasmic and nuclear estrogen receptors. A histochemical study on human mammary cancer and rabbit uterus

Consecutive serial cryostat-frozen sections of 157 human mammary carcinomas and the uteri of six immature New Zealand white rabbits were stained histochemically for cytoplasmic estrogen receptor (ER) and nuclear ER by a fluorescent estrogen compound (Fluorocep Estrogen, Zeus Technologies, Inc., Raritan, NJ) and by a monoclonal antibody immunoperoxidase technique (ER-ICA, Abbott Laboratories, North Chicago, IL), respectively. The percentage of the ER-positive cells in the cancer cell population under observation was estimated and recorded. The results of the cytoplasmic ER assay were compared with those of the nuclear ER assay in each tumor; all cancers with less than 10% ER-positive cancer cells were grouped together as ER-negative tumors, the cancers with 30% or more ER-positive cancer cells as ER-positive tumors, and those with 10% to 29% ER-positive cancer cells as borderline positive. According to this manner of classification, 94% to 97% of the ER-positive mammary carcinomas diagnosed by one histochemical assay would have been identified as such by the other with no more than 10% difference in the ER-positive cell counts. The majority of ER-positive breast cancer cells and practically all of the luminal lining cells of the immature rabbit endometrium had coexistent cytoplasmic and nuclear ER. In the mammary cancers containing less than 30% ER-positive cancer cells, there was a greater (up to 20%) discrepancy in positive cell counts between the cytoplasmic ER assay and the nuclear ER assay. This discrepancy may be due to sampling errors of small clones of ER-positive cancer cells in two adjacent sections, difference in antigenic determinants between the cytoplasmic and the nuclear ER, and the binding sites in the nuclear ER being preoccupied by estrogen. The findings of this study appear to support the hypothesis that there are ER in the cytoplasm and the nucleus of the mammary carcinoma cells and the epithelial cells of the endometrium.