Re-Evaluation of Clinical Parameters in Relation to Estrogen Receptor Assay in Predicting Response to Major Endocrine Ablation Therapy in Patients with Advanced Breast Cancer

The response to major endocrine ablation therapy (adrenalectomy with oophorectomy and its modifications) was evaluated from combining the variable of the presence or absence of the estrogen receptor (ER) in tumors, and 11 other clinical variables in 64 patients with advanced breast cancer. The variables used in computation were the age and menopausal status of the patients, the disease-free interval, the performance status, the site(s) of metastases (local chest wall, lymph node, bone, lung, and liver), urinary excretion of 17-ketosteroids (17-KS), and the 17-KS/17-OHCS ratio in urine. The probability of regression in the therapy was computed with Cox's linear logistic regression model. The single most important factor that contributed to the probability of regression was shown to be the presence or absence, not the concentration, of ER. In analyzing 38 patients with ER-positive tumors, the presence and amount of the liver metastases, and of the bone metastases, and the 17-KS/17-OHCS ratio in urine were all shown to be significant in giving the probability. Even when the results of ER assay of the tumors were not included in the computation, a formula of the probability of regression could be constructed from these three factors. It is suggested that in addition to the ER assay of breast cancer tissues, some biological characteristics of the patients may have significant relationships to the response to endocrine therapy.