Further studies of biochemical predictive tests in breast cancer.

This report extends our observations on the relationship between the therapy of breast cancer, estrogen binding and tissue enzymes. We have compared the dextran-coated charcoal method and the sucrose gradient analysis in determining estrogen receptors, and find a sub-group of receptor positive tumors--identifiable only by the latter technique--which we suggest may lead to an incorrect prediction of response to hormonal therapy. Data are also presented to suggest that enzyme analyses show promise in predicting responsiveness to present modes of combination chemotherapy of breast cancer.