Comparison of one first-generation and three second-generation methods for the determination of CA 125.
The monoclonal antibody OC125 (Centocor, Inc, Malvern, PA) was the basis for the first generation of one-step immunoradiometric assays (IRMA), used to detect the glycoprotein CA 125. Recently two-step IRMAs were developed: the CA 125 second-generation assays. In these new assays the CA 125 capture antibody is the M11 monoclonal antibody coated on a solid phase and the OC125 monoclonal antibody is used as tracer. We compared one first-generation radioassay and three second-generation assays (two radioassays and one ELISA) both analytically and clinically. The ELISA method showed the best within-assay precision and the best curve fitting characteristics. In the clinical comparison, none of the correlations between the first-generation and second-generation methods were really satisfactory; however, the cutoff level of 35 U/ml was confirmed. The four CA 125 assays do not yield equal results. As a consequence, the evolution of CA 125 serum concentrations during disease monitoring is not reliable when different determination methods are used consecutively.
Martin
M J
MJ
Department of Nuclear Medicine, Antwerp University Hospital, Belgium.
Blockx
P P
PP
D000704:Analysis of Variance; D000911:Antibodies, Monoclonal; D001331:Automation; D018394:CA-125 Antigen / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005260:Female; D006801:Humans; D015592:Immunoradiometric Assay / Q000379:methods; D009369:Neoplasms / Q000097:blood / Q000175:diagnosis*; D010051:Ovarian Neoplasms / Q000097:blood / Q000175:diagnosis; D012016:Reference Values; D012044:Regression Analysis; D015203:Reproducibility of Results
D000911:Antibodies, Monoclonal; D018394:CA-125 Antigen