Estrogen Receptors and Responses to Chemotherapy and Hormonal Therapy in Advanced Breast Cancer

To determine the correlation between the estrogen-receptor status and responses to chemotherapy or hormonal therapy, we retrospectively analyzed the clinical data of 143 patients with advanced breast cancer. Receptor contents were determined by a sucrose-gradient method and designated arbitrarily as "rich" or "poor." The response rate to chemotherapy was significantly higher in receptor-rich tumors (86 per cent) than in receptor-poor tumors (36 per cent) (P<0.001). Patients with receptor-rich tumors also responded favorably to hormonal therapy. However, there was no correlation between the responses to hormonal therapy and to chemotherapy when they were used sequentially, a phenomenon that may be attributed to the changes in tumor receptor content during the clinical course. These data suggest that separate factors associated with the response to chemotherapy may coexist with estrogen receptors in breast cancer. (N Engl J Med 299:1330–1334, 1978)