Breast carcinoma and plasma 17-beta-estradiol binding

The data relating to plasma steroid binding and transport (usually measured with dehydrotestosterone) are controversial. The plasma E2 binding of 79 breast carcinoma patients, 19 premenopausal and 60 postmenopausal, were compared to 46 controls, 21 premenopausal and 25 postmenopausal. In this study the authors removed the endogenous steroids with charcoal, incubated the plasma with 17-beta-E2 in non-saturation conditions, and used ammonium sulfate to precipitate the complex. The authors chose 17-beta-E2 as ligand because the plasma steroid binding system has not been shown to be homogeneous and because this binding function may vary independently for the different steroids. In these patients, the E2 binding was significantly (P less than 0.01) increased (85 +/- 11 pg/ml and 73 +/- 13 pg/ml in premenopausal and postmenopausal) compared to the normal controls (59 +/- 7 pg/ml and 58 +/- 5 pg/ml in premenopausal and postmenopausal women. It is still unclear whether this is a primary increase of the binding capacity or a reaction of the host for sequestering excess circulating E2. However, the small percentage of false-positives and false-negatives suggests that E2 binding could be used as a tumor marker in breast carcinoma.