Steroid receptors in breast cancer.

About 20-35% of patients with metastatic breast cancer obtain remissions after hormone treatment. Identifying those patients likely to benefit from the therapy has been made possible through analysis of the estrogen-receptor content of the cancer tissue. Two approaches may be used to determine whether or not the patient will respond to endocrine therapy: the quantity of estrogen receptor present in tumor cytosol and/or assay information obtained on both estrogen and progesterone receptors. Not all estrogen receptor containing breast cancers respond to therapy. Each primary tumor should be assayed for ER so that the assay information is available when needed at the time of disseminated disease. The tissue sample should be immediately chilled to ice temperature before it is transported to the laboratory. A peice of the tissue sample adjacent to the receptor assay piece should be sent to the pathology laboratory to be sure that the assayed piece is tumor tissue. Prolonged storage of tumor tissue prior to assay is to be discouraged. The most reliable and reproducible methods for cytosol estrogen receptor assay is sucrose density gradient sedimentation analysis and multiple point detran-coated charcoal assay analyzed by Scatchard plot. As other methods appear they should be validated against these methods. A quality control resource needs to be developed to support the conduct of clinical trails.