Quantitative estrogen receptor analyses: the response to endocrine and cytotoxic chemotherapy in human breast cancer and the disease-free interval.

The usefulness of estrogen receptor (ER) analyses was assessed in a variety of clinical situations. The predictive accuracy of the test is substantially increased by quantification. ER analyses accurately predict objective responses to endocrine therapy independently of other clinical prognostic criteria. In addition, ER positivity is associated with a decreased response rate to cytotoxic chemotherapy in patients with metastatic breast cancer. Finally, the presence of ER is positively associated with a prolonged disease-free interval independent of menopausal status, tumor size, and axillary lymph node involvement.