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

Abstract Background: Since the introduction of luminescent oxygen channeling immunoassays (LOCI™)-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™-based tumor marker assays for Dimension™ VISTA and electrochemiluminiscent immunoassays (ECLIA) for Cobas™ e411, for α-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™ VISTA 1500 and Cobas™ 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™ 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.