Alternative antibody for the detection of CA19-9 antigen: a European multicenter study for the evaluation of the analytical and clinical performance of the Access GI Monitor assay on the UniCel Dxl 800 Immunoassay System.

Abstract

BACKGROUND:

Gastrointestinal cancer antigen CA19-9 is known as a valuable marker for the management of patients with pancreatic cancer.

METHODS:

The analytical and clinical performance of the Access GI Monitor assay (Beckman Coulter) was evaluated on the UniCel Dxl 800 Immunoassay System at five different European sites and compared with a reference method, defined as CA19-9 on the Elecsys System (Roche Diagnostics).

RESULTS:

Total imprecision (%CV) of the GI Monitor ranged between 3.4% and 7.7%, and inter-laboratory reproducibility between 3.6% and 4.0%. Linearity upon dilution showed a mean recovery of 97.4% (SD + 7.2%). Endogenous interferents had no influence on GI Monitor levels (mean recoveries: hemoglobin 103%, bilirubin 106%, triglycerides 106%). There was no high-dose hook effect up to 115,000 kU/L. Clinical performance investigated in sera from 1811 individuals showed a good correlation between the Access GI Monitor and Elecsys CA19-9 (R = 0.959, slope = 1.004, intercept = +0.17). GI Monitor serum levels were low in healthy individuals (n = 267, median = 6.0 kU/L, 95th percentile=23.1 kU/L), higher in individuals with various benign diseases (n = 550, medians = 5.8-13.4 kU/L, 95th percentiles = 30.1-195.5 kU/L) and even higher in individuals suffering from various cancers (n = 995, medians = 8.4-233.8 kU/L, 95th percentiles = 53.7-13,902 kU/L). Optimal diagnostic accuracy for cancer detection against the relevant benign control group by the GI Monitor was found for pancreatic cancer [area under the curve (AUC) 0.83]. Results for the reference CA19-9 assay were comparable (AUC 0.85).

CONCLUSIONS:

The Access GI Monitor provides very good methodological characteristics and demonstrates an excellent analytical and clinical correlation with the Elecsys CA19-9. The GI Monitor shows the best diagnostic accuracy in pancreatic cancer. Our results also suggest a clinical value of the GI Monitor in other cancers.

• Authors: Petra Stieber, Rafael Molina, Massimo Gion, Axel Gressner, Frédéric Troalen, Stefan Holdenrieder, Jose Maria Auge, Matelda Zancan, Matthias Wycislo, Véronique Jarrige
• Journal: Clinical chemistry and laboratory medicine (Clin Chem Lab Med) Vol. 46 Issue 5 Pg. 600-11 ( 2008) ISSN: 1434-6621 [Print] Germany
• PMID: 18598202 (Publication Type: Comparative Study, Evaluation Study, Journal Article, Multicenter Study)

Chemical References

• Antibodies
• CA-19-9 Antigen

Topics

• Adolescent
• Adult
• Aged
• Aged, 80 and over
• Antibodies (chemistry)
• Area Under Curve
• CA-19-9 Antigen (blood)
• Europe
• Female
• Humans
• Immunoassay (instrumentation, methods)
• Male
• Middle Aged
• Pancreatic Neoplasms (blood, diagnosis)
• Reproducibility of Results