Steroid Receptors in Breast Cancer

Knowledge of the steroid receptor content of human breast cancer is important for proper diagnosis and for deciding the proper treatment for metastatic disease. Few patients whose breast cancers lack estrogen receptor will benefit from endocrine therapy, while more than half of patients with estrophilin-rich cancers will obtain objective remissions. The probability of objective response to endocrine therapy increases with an increase in the quantity of estrogen receptor in the cancer. Furthermore, patients whose cancers have both estrogen and progestin receptors have a better probability of response than patients whose lesions have only one of the receptors present, although even in such cases the response rate is higher than that seen in patients whose tumors lack both receptors. The data currently available suggest that receptor assays carried out on the primary tumor can be used for prediction of subsequent response to endocrine therapy, even at a later time of recurrent disease. Nonetheless, while sequential assays of receptors in lesions from the same patients are likely to be in agreement, when changes occur they tend to be reductions in amount of receptor or loss of receptor during disease progression . Breast cancer patients with receptor-positive tumors appear to have longer disease-free intervals and prolonged survival when compared with patients whose cancers lack ER, but clearly a part of the prolonged survival relates to response to endocrine therapies. Receptor positivity is frequently associated with well-differentiated tumors, while more poorly differentiated cancers, as well as medullary tumors, in general, and possibly cancers with significant lymphocytic infiltration, are more likely to be receptor negative. While there are some problems reproducing the exact quantitative receptor results among various laboratories assaying the same breast cancer, standard biochemical assays are still the only clinically proven and generally accepted procedure for assessing receptor status of a tumor. Histochemical assays based both on the steroid content of a tumor or using steroid-protein fluorescein complexes, while showing some correlation with standard biochemical assays for estrogen receptor, do not appear to detect receptor protein itself and can not be used instead of standard receptor assays. With the recent availability of monoclonal antibodies to the estrogen receptor, newer assays based on immunochemical procedures are under development and can be expected to provide simpler, less expensive, and more useful biochemical as well as immunohistochemical methods for receptor determination.(ABSTRACT TRUNCATED AT 400 WORDS)