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

Tumor estrogen receptor status in women with advanced breast cancer was correlated with clinical response to cytotoxic chemotherapy in a retrospective study. Following an extramural review of the clinical data of 40 patients, 26 responded to chemotherapy (65%). The response rate in 19 receptor-rich tumors was 89% and in 21 receptor-poor tumors, 43% (P < 0.01). The lowest response rate (14%) was observed in seven postmenopausal patients with receptor-poor tumors. Clinical characteristics of patients and variants in chemotherapy programs failed to explain the favorable response of receptor-rich tumors to cytotoxic chemotherapy.