The nuclear estrogen receptor assay applied to human breast cancer: Criteria for its use

Abstract

The nuclear estrogen receptor (RnE) content of 33 specimens of primary breast cancer was measured, in an attempt to establish a correlation with the cytosolic estrogen receptor (RcE) status and the criteria for its laboratory usage. RnE was measured in crude nuclear suspensions by 3H-estradiol exchange assay (quadruplicate incubations with a single 2.8 nM 3H-estradiol concentration ± 2uM DES), and RcE by means of the dextrane-charcoal method. 58% of the tumour were RnE positive (significant differences between total and non-specific binding, at p<0.05 level) and 48% were RcE-positive (RcE 10 fmol/mg protein). Some pre-menopause women, in whom RcE was on the borderline or lower, showed high RnE. When the RcE assay is about the borderline or offers some doubt in regard to performance, and in the cause of tumours in pre-menopausal women, it would be interesting to measure the RnE in order to exclude false-negative results.