Alternative antibody for the detection of CA15-3 antigen: a European multicenter study for the evaluation of the analytical and clinical performance of the Access (R) BR Monitor assay on the UniCel (R) Dxl 800 Immunoassay System

Background: Cancer antigen CA15-3 antigen is known as a valuable
marker for the management of breast cancer. Methods: The analytical
and clinical performance of the Access' BR Monitor Immunoassay
System (Beckman Coulter) was evaluated at five different European
sites and compared with a reference system, defined as CA15-3 on
the Elecsys(R) System (Roche Diagnostics). Results: Total
imprecision (%CV) of the BR Monitor ranged between 5.5% and 11.7%,
and inter-laboratory reproducibility between 3.4% and 5.1%.
Linearity upon dilution showed a mean recovery of 98.5%
(SD+/-9.1%). Endogenous interferents had no influence on BR Monitor
levels (mean recoveries: hemoglobin 112%, bilirubin 111%,
triglycerides 108%). There was no high-dose hook effect up to
13,540 kU/L. Clinical performance investigated in sera from 1811
individuals showed a general correlation between the Access BR
Monitor and Elecsys CA15-3 (R = 0.797), with a slope of 1.383.
CA15-3 serum levels, as measured by the BR Monitor, were low in
healthy individuals (n = 267, median = 11.9 kU/L, 95th percentile =
23.5 kU/L), higher in individuals with various benign diseases (n =
549, medians = 11.3-15.6 kU/L, 95th percentiles = 21.6-54.6 kU/L)
and even higher in individuals suffering from various cancers (n =
995, medians = 11.2-22.8 kU/L, 95th percentiles = 30.0-429.7 kU/L).
Best diagnostic accuracy for cancer detection against the relevant
benign control group by the BR Monitor was found for locoregional
and metastatic breast cancer, as well as for ovarian cancer {[}area
under the curve (AUC) 0.619, 0.897 and 0.774]. Results for the
reference CA15-3 assay were comparable (AUC 0.611, 0.887 and
0.818). Conclusions: The Access BR Monitor provides accurate
methodological characteristics and demonstrates an analytical and
clinical correlation with Elecsys CA15-3. Best diagnostic accuracy
for the BR Monitor was found in breast and ovarian cancer. Our
results also suggest a clinical value of the BR Monitor in other
cancers.