Open Access

ARTICLE

Complexed prostate specifi c antigen: better test in the diagnosis of prostate cancer for the clinically relevant 2.5-4 ng/ml total PSA range

Nilgun Mutlu¹, Levent N. Türkeri², Faruk Yencilek³, Aslan Demir², Kaya Emerk⁴

1 Department of Biochemistry, Yeditepe University Hospital, Istanbul, Turkey
2 Department of Urology, Marmara University Hospital, Istanbul, Turkey
3 Department of Urology, Yeditepe University Hospital, Istanbul, Turkey
4 Department of Biochemistry, Marmara University School of Medicine, Istanbul, Turkey
Address correspondence to Dr. Levent N. Türkeri, Tophanelioglu cad. No: 13-15, 34660 Altunizade, Istanbul, Turkey

Canadian Journal of Urology 2009, 16(2), 4558-4567.

Abstract

Background: Data on utilizing complexed prostate specific antigen (cPSA) offering increased diagnostic performance over other available clinical parameters in diagnosis of prostate cancer is still controversial. Our objective was to determine diagnostic performance of cPSA compared to total prostate specific antigen (tPSA) and corresponding ratios for possible routine application.
Methods: In a prospective study including overall 315 consecutive men, 177 patients with suspicious digital rectal examination, and/or tPSA value ≥ 2.5 ng/ml underwent prostate biopsy. Serum samples for tPSA, cPSA and free PSA were analyzed using automated chemiluminometric technology.
Results: Area under the curve (AUC) for cPSA, although greater, was not statistically different compared to that of tPSA (p = 0.253). AUCs of f/c, f/t and c/t ratios were all found significantly inferior. At clinically relevant 2.37 ng/ml threshold, cPSA performed with 85% sensitivity and significantly higher specificity of 63.1%, compared to same sensitivity and specificity of 57.2% at a 3.00 ng/ml cut-off for tPSA.
Conclusions: Utilizing automated assay systems at predetermined cut-off value for cPSA we would be able to save 27.1% of the biopsies while missing 13.4% of the cancers. Therefore, results of this study indicate higher discriminatory power of cPSA in diagnosis of prostate cancer for clinically relevant 2.5-4 ng/ml tPSA range.

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