Abstract
In a retrospective study we determined the relation between estrogen receptors and the response rate to cytotoxic chemotherapy in 70 patients with metastatic breast cancer. Thirty-four of 45 patients with low or absent estrogen-receptor values (<10 fmol per milligram of cytoplasmic protein) had objective responses to chemotherapy, whereas only three of 25 patients with higher values (>10 fmol per milligram of cytoplasmic protein) responded (P<0.0001). There were no statistically significant differences between the two groups in age, menopausal status, disease-free interval, Karnofsky index or prior therapy. Differences in sites of involvement or type of chemotherapy did not account for the increased response rate in receptor-negative patients. We conclude that estrogen-receptor values are an important predictor of response to cytotoxic chemotherapy in metastatic breast cancer. (N Engl J Med 298:1223–1228, 1978)
MOST steroid hormone actions are mediated by an initial binding of the hormone to specific cytoplasmic receptor proteins.
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Such receptors are present in about 50 per cent of breast-tumor specimens.
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Furthermore, their presence is clearly associated with a greatly increased likelihood of response of metastatic disease to endocrine manipulations whereas absence of estrogen receptor decreases the likelihood of response to endocrine therapy to less than 10 per cent.
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Thus, knowledge of estrogen-receptor status can increase the accuracy of patient selection for endocrine therapy.
Several lines of evidence suggested to us that it might be worthwhile to examine human breast-cancer samples . . .
