Presurgical radiotherapy decreases the concentrations of estrogen and progesterone receptors in human breast cancer: A 200-patient study

The concentrations of cytosol estrogen (RE) and progesterone (RP) receptors were evaluated in human breast cancer either pretreated or untreated by radiotherapy. Receptor sites were assayed within a week following surgery by using the classical dextran-coated charcoal technique with three saturating concentrations of (3H) 17β estradiol and (3H) R5020 and by correcting for nonsaturable binding estimated in parallel with an excess of nonradioactive ligand. Only tissue containing cancer cells as determined by a pathologist was assayed for receptors.