Free and Complexed Prostate-Specific Antigen (PSA) in the Early Detection of Prostate Cancer

Abstract

We evaluated the analytical performance and diagnostic utility of complexed prostate-specific antigen (CPSA) and their ratios, complexed-to-total PSA (C/T PSA) and free-to-complexed PSA (F/C PSA), in comparison with the total PSA (TPSA) and free-to-total PSA ratio (F/T PSA) as means of diagnosing prostate cancer (PC). Samples (n=101) were drawn from men with no evidence of malignancy (n=80) and from men with PC (n=21) at biopsy. For determination of the F/T PSA ratio, the DPC Immulite-2000 method was used; and the Bayer Immuno-1 CPSA and TPSA assays were used to determine the C/T PSA ratio. The Bayer Immuno-1 CPSA assay provides accurate and precise CPSA values in human serum. The performance of the different forms and ratios was compared using receiver operating characteristic curve analysis. CPSA had the greatest area under the curve (AUC, 0.689) although it was not statistically different from the other parameters. A cut-off value of 4.66 ng/ml for CPSA provided a specificity of 38% and a sensitivity of 93%. The F/C PSA ratio maintained a sensitivity of 93% and had an increased specificity of 41%. The measurement of CPSA provides a slight increase in specificity compared with the use of the TPSA in the early detection of prostate cancer.

Kallikrein-related peptidases (KLKs): a gene family of novel cancer biomarkers

“…Along with digital rectal examination, the PSA test has become part of the routine medical checkup in many countries during the last decades (79) . It is common knowledge that increased preoperative serum PSA levels constitute an independent unfavorable prognostic biomarker in prostate cancer, positively correlating with advanced-stage disease and predicting poor clinical outcome.…”

Effect of prostate manipulation on the serum levels of complexed prostate‐specific antigen and total prostate‐specific antigen

“…Although no study has been conclusive, some have shown promising results with an increased specificity over tPSA in the detection of prostate cancer while other studies have shown an equivalence to the f/t PSA. [15][16][17][18][19][20] There also is a cost advantage in using cPSA. In comparison to the measurement of the f/t PSA, which requires two assays, the measurement of cPSA requires only one assay.…”

“…Numerous studies have been performed looking at the performance of complexed PSA (cPSA) assays. Although no study has been conclusive, some have shown promising results with an increased specificity over tPSA in the detection of prostate cancer while other studies have shown an equivalence to the f/t PSA 15–20 …”