Significance of estrogen receptor assay in cytotoxic chemotherapy in relation to previous endocrine therapy of advanced breast cancer patients.

In 36 patients with advanced breast cancer, most of whom had been subjected to major endocrine ablation therapy such as bilateral adrenalectomy, correlation between the presence or absence of estrogen receptor (ER) in tumors and response to chemotherapy was investigated. Complete or partial response was obtained in 6 of 14 (42.6%) patients with ER-positive tumors and in 3 of 22 (13.6%) patients with ER-negative tumors (P = 0.1). The response to chemotherapy was not influenced by the concentration of ER in tumors. Distribution of the duration of regression readings and the survival time was not significantly different between the patients with ER-positive and -negative tumors. Some regimens which did not include adriamycin, such as MFC (mitomycin-C, 5-fluorouracil, and cytosine arabinoside) had a good effect on the ER-positive cases, whereas the response to regimens including adriamycin was not influenced by the ER positiveness of the tumors. In the classification of some clinical parameters of the patients, response of the patients with ER-negative tumors does not seem to be better than that of the patients with ER-positive tumors. Responses to the major endocrine ablation therapy and also to the subsequently carried out chemotherapy were influenced by the presence or absence of ER in tumors before the endocrine therapy.