Abstract

PIP: This article reviews the current knowledge on estrogen receptors and their relationship to response to endocrine therapy to assist surgeons in management of breast cancer patients. The findings can be summarized as follows: 1) estrogen receptors can be assayed in about 70% of breast cancer tissues; activity measurements are based on arbitrary cutoffs. 2) No method of assay for estrogen receptors is entirely satisfactory at present; most methods require substantial tissue sampling and measure only empty receptor sites. 3) The wide range of receptor status found among patients may be influenced by menstrual status, tumor heterogeneity, and biopsy site. 4) Estrogen receptor activity in primary tumors is related to tumor grade, cellularity, elastosis, presence of other receptors, and other biochemical factors, all of which can serve as indices for differentiation. 5) A strong correlation exists between the presence of receptor activity and response to endocrine therapy in most cases of advanced disease, but this correlation has not been shown for chemotherapy. 6) Receptor status helps indicate prognosis, especially receptor positive tumors which are associated with lower recurrence rates than receptor negative tumors, at least in postmenopausal women.