Alternative antibody for the detection of CA15-3 antigen: a European multicenter study for the evaluation of the analytical and clinical performance of the Access BR Monitor assay on the UniCel DxI 800 Immunoassay System

Background: Cancer antigen CA15-3 antigen is known as a valuable marker for the management of breast cancer. Methods: The analytical and clinical performance of the Access BR Monitor Immunoassay System (Beckman Coulter) was evaluated at five different European sites and compared with a reference system, defined as CA15-3 on the Elecsys System (Roche Diagnostics). Results: Total imprecision (%CV) of the BR Monitor ranged between 5.5% and 11.7%, and inter-laboratory reproducibility between 3.4% and 5.1%. Linearity upon dilution showed a mean recovery of 98.5% (SD"9.1%). Endogenous interferents had no influence on BR Monitor levels (mean recoveries: hemoglobin 112%, bilirubin 111%, triglycerides 108%). There was no high-dose hook effect up to 13,540 kU/L. Clinical performance investigated in sera from 1811 individuals showed a general correlation between the Access BR Monitor and Elecsys CA15-3 (Rs0.797), with a slope of 1.383. CA15-3 serum levels, as measured by the BR Monitor, were low in healthy individuals (ns267, medians11.9 kU/L, 95th percentiles23.5 kU/L), higher in individuals with various benign diseases (ns549, medianss11.3–15.6 kU/L, 95th percentiless21.6–54.6 kU/L) and even higher in *Corresponding author: Dr. med. Petra Stieber, Institut für Klinische Chemie, Klinikum der Universität München, Marchioninistr. 15, 81366 München, Germany Phone: q49-89-7095-3115, Fax: q49-89-7095-6298, E-mail: [email protected] Received October 4, 2007; accepted January 28, 2008 individuals suffering from various cancers (ns995, medianss11.2–22.8 kU/L, 95th percentiless 30.0–429.7 kU/L). Best diagnostic accuracy for cancer detection against the relevant benign control group by the BR Monitor was found for locoregional and metastatic breast cancer, as well as for ovarian cancer warea under the curve (AUC) 0.619, 0.897 and 0.774x. Results for the reference CA15-3 assay were comparable (AUC 0.611, 0.887 and 0.818). Conclusions: The Access BR Monitor provides accurate methodological characteristics and demonstrates an analytical and clinical correlation with Elecsys CA15-3. Best diagnostic accuracy for the BR Monitor was found in breast and ovarian cancer. Our results also suggest a clinical value of the BR Monitor in other cancers. Clin Chem Lab Med 2008;46:612–22.