Analysis of a serum test for prostate cancer that detects a second epitope of EPCA-2.
BACKGROUND
We have previously shown that EPCA-2 can serve as a highly specific and sensitive serum marker for prostate cancer. As a component of our validation of this marker, we have performed an initial evaluation of an assay that detects a distinct epitope of the same protein: EPCA-2.19. The goals of this study are to characterize the sensitivity and specificity of the EPCA-2.19 assay, in a non-screening population, and to demonstrate that such test based has similar characteristics as the initial assay produced.


METHODS
Three hundred twenty-eight serum samples from men with PSA values < and >2.5 ng/ml who had negative biopsies, men with BPH, men with organ-confined and non-organ-confined prostate cancer, as well as control populations were evaluated using the EPCA-2.19 assay.


RESULTS
At a cut-off of 0.5 ng/ml and above, EPCA-2.19 has a specificity of 94% and a sensitivity of 91% in separating normal men with PSA < and >2.5 ng/ml, and men with BPH from those with prostate cancer. Receiver Operator Curve analyses of the EPCA-2.19 assay demonstrate an area under the curve of 0.982 (95% CI 0.952-0.996, P < 0.0001).


CONCLUSIONS
This study confirms our earlier findings that the assay that detects against a second epitope of EPCA-2 yields almost identical results to those obtained for the first published assay (EPCA-2.22). While this provides some validation of our earlier studies, larger multi-institutional studies still need to be performed.
The Brady Urological Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21287, USA.
Eddy S
ES
Leman
Ahmed
A
Magheli
Grant W
GW
Cannon
Leslie
L
Mangold
Alan W
AW
Partin
Robert H
RH
Getzenberg
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000951:Antigens, Neoplasm / Q000097:blood*; D014408:Biomarkers, Tumor / Q000097:blood*; D001706:Biopsy; D000939:Epitopes / Q000097:blood*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008297:Male; D008403:Mass Screening / Q000379:methods; D008875:Middle Aged; D011467:Prostate / Q000473:pathology; D011470:Prostatic Hyperplasia / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis*; D012372:ROC Curve; D012680:Sensitivity and Specificity
D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D000939:Epitopes; C504719:early prostate cancer antigen, human; C542166:early prostate cancer antigen-2, human