Method comparison of tumor markers assessed by LOCI™- and ECLIA-based technologies

Background: Since the introduction of luminescent oxygen channeling immunoassays (LOCI (TM))- based assays in the daily laboratory routine of tumor marker measurements, only a small number of method comparisons with established immunoassays have been published. We performed a method comparison between LOCI (TM) - based tumor marker assays for Dimension (TM) VISTA and electrochemiluminiscent immunoassays (ECLIA) for Cobas (TM) e411, for alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), CA 125, CA 15- 3, CA 19-9, prostate-specific antigen (PSA) and free PSA (fPSA). Methods: Tumor markers were assessed in 1088 sera from routine diagnostics on the Dimension (TM) VISTA 1500 and Cobas (TM) e411 analyzers. Results: Strong correlations were achieved for PSA ( r = 0.999), AFP ( r = 0.994) and CEA ( r = 0.993). Results were quite comparable as only minor slopes of 1.05 ( PSA), 1.02 AFP) and 0.94 ( CEA), respectively, were found. However, correlations for CA 125 ( r = 0.976), CA 19- 9 ( r = 0.960), fPSA ( r = 0.950) and CA 15- 3 ( r = 0.940) were only moderate, and considerable slopes were observed for these markers with higher values for CA 19- 9 ( slope 1.50) and lower ones for CA 15- 3 ( 0.76), fPSA ( 0.75) and CA 125 ( 0.64), for Dimension (TM) VISTA 1500. Conclusions: We found excellent correlations and comparable values for AFP, CEA and PSA, but only moderate correlations for fPSA, CA 125, CA 15- 3 and CA 19- 9. The slopes for CA 19- 9, CA 15- 3, fPSA and CA 125 have to be considered when analysis methods for tumor markers are changed.