Reliability of estrogen receptors in predicting hormonal responsiveness in treatment of metastatic breast cancer.

A series of 112 female breast cancer patients provided 123 tissue samples for this study analyzing estrogen receptor binding activity (ER) and clinical correlations of such activity with hormonal responsiveness in 35 of these patients. 51% of patients were ER positive. There were no significant differences between ER positive and negative patients with regard to the following possible prognostic variables: race biopsy site dominant metastatic site or extent of disease. There was however among 59 patients with metastatic disease a difference in disease-free interval with patients having longer disease-free intervals being ER positive more frequently. Of 28 evaluable patients who received hormone therapy for metastasis 55% of ER positive patients responded. Progesterone receptors were evaluated in 42 specimens and overall 18 (43%) contained detectable receptor. 7 patients were evaluable for hormonal responsiveness; all 3 patients with detectable ER and progesterone receptor responded 2 of 3 with ER positive and no progesterone receptor responded and 1 without ER but with progesterone receptor responded. Problems with false-negative results in hormone receptor assays are discussed.