Interchangeability of measurements of CA 19-9 in serum with four frequently used assays: an update.
BACKGROUND
CA 19-9 is a marker principally related to pancreatic and gall bladder cancer. Although its determination has no value in screening for these malignancies, it is used in post-operative monitoring and during chemotherapeutic treatment of confirmed disease. Measurements during follow-up must be comparable and must be performed with standard, validated methods.


METHODS
We compared four routinely used analytical systems for CA 19-9 determination: the Architect i2000 and AxSYM systems from Abbott Laboratories, the Elecsys 1010 from Roche Diagnostics, and the KRYPTOR system from Brahms Diagnostics. We evaluated the analytical performance of the four systems and compared measurements of CA 19-9 values, which covered the whole analytical range.


RESULTS
The analytical performance and accuracy of the four systems were fairly good, but Passing-Bablok regression and mountain plots showed significant differences in CA 19-9 values measured with the four platforms.


CONCLUSIONS
Our data indicate that during tumor follow-up, the use of the same system is appropriate to avoid the risk of a variation due to the method rather than the disease. Moreover, whenever a change in analytical equipment is required, careful analysis of CA 19-9 results must be undertaken.
Passerini
Rita
R
Laboratory Medicine Unit, European Institute of Oncology, Milan, Italy. rita.passerini@ieo.it
Riggio
Daniela
D
Salvatici
Michela
M
Zorzino
Laura
L
Radice
Davide
D
Sandri
Maria Teresa
MT
D001681:Biological Assay; D018395:CA-19-9 Antigen / Q000097:blood* / Q000276:immunology; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods* / Q000592:standards; D009369:Neoplasms / Q000097:blood* / Q000276:immunology / Q000628:therapy; D011933:Reagent Kits, Diagnostic / Q000592:standards; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D018395:CA-19-9 Antigen; D011933:Reagent Kits, Diagnostic