Yonsei Med J.  2012 May;53(3):557-564. 10.3349/ymj.2012.53.3.557.

Evaluation of the UniCel(TM) DxI 800 Immunoassay Analyzer in Measuring Five Tumor Markers

• Park Y
• Park Y
• Park J
• Kim HS

• KMID: 1776991
• DOI: http://doi.org/10.3349/ymj.2012.53.3.557

Abstract

PURPOSE
Tumor marker concentrations in a given specimen measured by different analyzers vary according to assay methods, epitopes for antibodies used, and reagent specificities. Although great effort in quality assessment has been instituted, discrepancies among results from different analyzers are still present. We evaluated the assay performance of the UniCel(TM) DxI 800 automated analyzer in measuring the alpha-fetoprotein (AFP), carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 125, CA 15-3 and CA 19-9 tumor markers.
MATERIALS AND METHODS
The linearity and precision performance of the five tumor marker assays were evaluated, and concentrations of the respective markers as measured by DxI were compared to those measured by other conventional analyzers (ADVIA Centaur(TM) and Vitros(TM) ECi) using 200 specimens collected from 100 healthy persons and 100 patients with respective cancers.
RESULTS
The linear fits for all five tumor markers were statistically acceptable (F=4648 for AFP, F=15846 for CEA, F=6445 for CA 125, F=2285 for CA 15-3, F=7459 for CA 19-9; p<0.0001 for all). The imprecision of each tumor marker assay was less than 5% coefficient of variation, except for low and high concentrations of AFP. The results from UniCel(TM) DxI 800 were highly correlated with those from other analyzers.
CONCLUSION
Our results demonstrate that UniCel(TM) DxI 800 has good linearity and precision performance for the tumor markers assayed in this study. However, there were discrepancies between assaying methods. Efforts to standardize tumor marker assays should be undertaken, and the redetermination of cut-off levels is necessary when developing methods of analyzing tumor markers.

Keyword

Alpha-fetoprotein (AFP); CA 125; CA 15-3; CA 19-9; carcinoembryonic antigen (CEA); tumor markers

MeSH Terms

CA-125 Antigen/blood
CA-19-9 Antigen/blood
Carcinoembryonic Antigen/blood
Humans
Immunoassay/*instrumentation/*methods
Tumor Markers, Biological/*blood
alpha-Fetoproteins/metabolism

Figure

• 

  Fig. 1 Linearity of the five tumor marker assays performed by UniCel™ DxI 800. The observed mean tumor marker levels showed excellent linear responses to the expected values (p<0.001). (A) The linearity range of the CEA assay was from 0.80 to 951.41 µg/L (R2=0.9997). (B) The AFP assay was linear in the range between 1.86 and 2092.91 µg/L (R2=0.9991). (C) The CA 15-3 assay showed linear responses to the expected concentrations in the range of 5.55 to 633.45 kU/L (R2=0.9983). (D) The CA 125 assay was verified to be linear at the concentrations between 7.68 and 1752.53 kU/L (R2=0.9994). (E) Linearity of the CA 19-9 assay was validated in the range of 0.80 to 1389.73 kU/L (R2=0.9995). CEA, carcinoembryonic antigen; AFP, alpha-fetoprotein; CA, carbohydrate antigen.

• 

  Fig. 2 Comparison of the results of five tumor markers measured by the UniCel™ DxI 800 with those measured by other instruments using Bland and Altman difference plots. The solid line indicates the mean difference between the methods, and the dashed lines indicate the upper and lower 95% confidence limits of the difference between the methods. (A) The mean difference of CEA was 5.62 µg/L [95% confidence interval (CI), -6.53 to 17.77 µg/L]. (B) The mean difference of AFP was -145.39 µg/L (95% CI, -220.47 to -70.32 µg/L). (C) The mean difference of CA 15-3 was -27.59 kU/L (95% CI, -36.24 to -18.94 kU/L). (D) The mean difference of CA 125 was 26.73 kU/L (95% CI, 3.72 to 49.74 kU/L). (E) The mean difference of CA 19-9 was -209.59 kU/L (95% CI, -312.58 to -106.60 kU/L). CEA, carcinoembryonic antigen; AFP, alpha-fetoprotein; CA, carbohydrate antigen.

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