EVALUATION OF 2ND GENERATION CA-125 ASSAYS

Objective: This study was performed in order to evaluate and compare t he serum CA 125 values obtained using an immunoradiometric (IRMA-II) a nd an immunoenzymatic (ETI-II) second generation assay, and to establi sh whether or not the two methods may be used interchangeably. Study d esign: Serum CA 125 levels were measured in parallel using IRMA-II and ETI-II CA 125 assays (Sorin Biomedical), in 82 women with benign or m alignant gynecological diseases. Statistical analysis was performed by linear regression analysis and Wilcoxon's test. Results. Serum CA 125 levels measured using the immunoenzymatic method were lower than thos e obtained by the immunoradiometric assay. The largest discrepancies b etween the two methods were found at concentrations of 35-100 U/ml, wi thin which fall cutoff values for the immunoradiometric assay. The cut off values of 35 or 65 U/ml, frequently used in the original immunorad iometric assay and retained for the immunoradiometric second generatio n assay, corresponded to 18 and 47 U/ml in the immunoenzymatic second generation assay. Conclusion: The discrepancies in CA 125 results obta ined by the two detection methods imply that the cutoff values used in the immunoenzymatic procedure should have a lower reference value in order to eliminate high rates of false negative results. Furthermore, their interchangeable use should be avoided in the monitoring of ovari an cancer and other gynecological diseases.