Analytical performance of CA 19.9, CA 125 and CA 15.3 assays as observed through an external quality assessment...

Immunoassays of the tumor markers CA 19.9, CA125 and CA 15.3 are generally acknowledged to be a useful tool in the management of cancer patients. As a consequence, many methods developed by different companies are now commercially available. However, discrepancies have been described in the results of marker determinations even when the same monoclonal antibody was used. An external quality assessment (EQA) was carried out; starting from 1989 about 110 laboratories participated; since December 1991 the program was linked with the interlaboratory program Oncocheck organized by the Service de Radiopharmacie et Radioanalyse, University of Lyon. At present more than 200 laboratories of many European countries are involved: cumulatively 47 quality control samples have been prepared and sent to the participants. This manuscript is a report on data collected for CA 19.9, CA 125, and CA 15.3.