Estrogen-receptor status and response to chemotherapy in early and advanced breast cancer.

The value of estrogen receptor (ER) status in the prediction of tumor response to combination chemotherapy was retrospectively analyzed in breast cancer patients selected for prospective controlled trials of chemotherapy (85 with advanced disease and 256 with operable tumors). All patients were previously untreated with either chemotherapy or endocrine therapy, and in all instances drug therapy was applied at the time of primary treatment. The ER status was considered positive in 54% of women with advanced disease and in 70% of women with operable breast tumor and positive axillary nodes, respectively. About 12% of patients were considered to have borderline ER. The response to drug therapy (complete plus partial remission in advanced breast cancer and 3-year relapse-free survival after mastectomy, respectively) was not significantly different between ER+ and ER- tumors. The comparative results of ER+ vs ER- patients were similar whether the cutoff point for ER+ t-mors was greater than 5 or greater than 10 fmol/mg cytosol protein. The present results indicate that in advanced and early breast cancer combination chemotherapy is effective regardless of ER status. Therefore, in the presence of ER+ tumors there is no reason to delay the early administration of effective chemotherapy. This is particularly true both in the presence of rapidly progressing metastatic disease and in the adjuvant setting.