The role of estrogen receptor status in predicting the response of carcinoma of the breast to adjuvant chemotherapy

This study was undertaken to determine if there was any correlation between the estrogen receptor status and the response of patients with operable carcinoma of the breast to adjuvant chemotherapy. Seventy-seven patients with metastases to the axillary lymph nodes who were receiving adjuvant chemotherapy following a modified radical mastectomy were studied. During the period of study, 12 of 34 estrogen receptor-positive tumors recurred, with a mean disease-free interval of 17.8 months, and 19 of 43 estrogen receptor-negative tumors recurred, with a disease-free interval of 15.2 months. Statistical analysis of recurrence at two years showed no difference between these two groups. Only one patient of 18 in the premenopausal group of women with estrogen receptor-positive tumors, however, had a recurrence compared with 11 of 24 patients with estrogen receptor-negative tumors. This difference was highly statistically significant, p>0.0005. We have concluded that the estrogen receptor status is not a reliable indicator of response to adjuvant chemotherapy for all patients. Our data do indicate a positive correlation between response to adjuvant chemotherapy and estrogen receptor status in the premenopausal group of patients and suggest that adjuvant chemotherapy in the premenopausal group of patients may be exerting some of its effect by ovarian suppression rather than by a solely cytotoxic effect on cancer cells of the breast.