Estrogen receptors in breast cancer

Of 1100 women whose primary and/or metastatic breast cancers have been analyzed for estrophilin, 30% are receptor‐rich and 70% receptor‐poor. On the basis of 134 treated patients, nearly two‐thirds of the receptor‐rich group can expect objective benefit from endocrine therapy, whereas few if any of the receptor‐poor patients will respond. Thus, estrophilin assay indicates the proper type of therapy for 85 to 90% of women with advanced breast cancer. Analysis of the primary tumor in the mastectomy specimen offers promise in predicting hormone dependency in metastases that appear up to 5 years later.