Steroid receptors in breast cancer: Sources of inter-laboratory variation in dextran-charcoal assays

Abstract

The presently recognized correlations between various clinical parameters and the concentrations of estrogen and progesterone receptors in breast cancer biopsies are largely based on receptor values obtained using the dextran-coated charcoal (DCC) method. This assay method is highly sensitive to slight changes in assay protocol, and differences in assay methodology may account for the wide variation in proportions of receptor positive patients reported by different centers. A survey of various aspects of the assay method that may lead to reproducible, systematic differences in concentrations of receptor levels is presented; and methods of compensating for or correcting these potential differences are discussed. The following aspects are considered: a) constitution of biopsy tissue, b) method of tissue homogenization, c) absorption of ligands to surfaces, d) inclusion of molybdate in the assay buffer, e) composition of the DCC slurry, and f) handling of samples for liquid scintillation counting. Differences in methods used to homogenize tissue in Europe and the U.S.A. may account for differences observed in the correlation of DCC assay results obtained using the recently-introduced monoclonal ER-EIA technique.

Creatine kinase BB isoenzyme levels in tumour cytosols and survival of breast cancer patients

“…ERs and PRs were measured with the dextran-coated charcoal (DCC) method (Thorphe et al, 1986(Thorphe et al, , 1987 and the results were grouped into receptor-positive and -negative categories based on a cut-off value of 10 fmol mg-' total protein.…”

Comparison of immunohistochemistry with immunoassay (ELISA) for the detection of components of the plasminogen activation system in human tumour tissue

“…For the set of 33 samples of various cancer types, two buffers were compared for their extraction efficiency: (i) a phosphate buffer: 10 mM K 2 HPO 4 /KH 2 PO 4 , 1.5 mM K 2 -EDTA, 10 mM monothioglycerol, 10% (v v -1 ) glycerol, 10 mM sodium molybdate (pH = 7.5) (Thorpe, 1987) and (ii) a detergent-containing Tris buffer: 0.1 M Tris-HCl (pH = 8.1), 1% (w v -1 ) Triton X-114, 10 mM EDTA, 10 µg ml -1 aprotinin (Behrendt et al, 1990).…”

Promoter methylation of BRCA1 in triple-negative breast cancer predicts sensitivity to adjuvant chemotherapy

“…ER and PR expression in the breast tumors were measured by using a dextran-coated charcoal assay as previously described [19]. MA) were used as the labeled ligands for ER and PR analyses, respectively.…”