The clinical value of multiple steroid receptor assays in breast cancer management.

Measurement of cytoplasmic estrogen (REc) and progesterone (RPc) receptors in human breast tumors together with estrogen receptor activity in the residual pellet ("nuclear" REN) provides a more accurate prediction of hormonal dependence that REc alone. Of 74 patients with advanced metastatic breast cancer, 57% of those with REc+ tumors had an objective response to endocrine manipulation. Of 51 patients whose tumor was assayed for both REc and RPc activity, 9 of 12 patients with REc+ RPc+ tumors showed remission, whereas only 3 of 30 patients with REc- RPc-, 2 of 6 with REc+ RPc-, and 2 of 3 with REc- RPc+ tumors had a clinical response. In a group of 19 patients where triple assay was performed, 5 of 6 with tumors positive for all three receptors responded, whereas 9 patients with triple negative tumors all showed no remission. Fifty-nine percent of primary and 60% of metastatic tumors with REc+ activity were also shown to be RPc+. Thirteen percent of REc- tumors were RPc+. Patients with REc+ RPc+ primary tumors tended to have a longer disease-free interval than patients with RPc- tumors, irrespective of whether the tumors were REc+ or REc-. In the light of the possibility of employing receptor status of the primary tumor to predict hormonal responsiveness in subsequent recurrences, a comparison is made of receptor status measured in primary tumors and metastases.