A long way to go for the harmonization of four immunoassays for carcinoembryonic antigen.

ABSTRACT

BACKGROUND: Carcinoembryonic antigen (CEA) is one of the most widely used tumor markers worldwide. CEA immunoassays often yield different results. The objective of the present study was to investigate the current state of harmonization among CEA tests. METHODS: A total of 94 individual serum samples were divided into 3 subsets and measured in triplicate using 4 assays, Abbott Architect i2000SR, Beckman Access DXI800, Roche Cobas e601, and Siemens Advia Centaur XP. The standards from each manufacturer and the 1st International Reference Preparation (IRP) 73/601 of the World Health Organization were measured as unknowns in parallel with the patient samples using the 4 assays. The results of an external quality assessment (EQA) scheme for CEA were also analyzed. RESULTS: A perfect correlation was not observed between any 2 assays, and the values obtained using the 4 assays were different for the detection of 94 individual patient serum samples. No consistency was detected in the CEA results evaluated by various assays for EQA samples, individual patient samples, the standards from each manufacturer, and the WHO IRP 73/601. CONCLUSIONS: Harmonization of the CEA results obtained using the 4 immunoassays has not yet been achieved.