Comparison of the Clinical Validity of Free Prostate–Specific Antigen, Alpha–1 Antichymotrypsin–Bound Prostate–Specific Antigen and Complexed Prostate–Specific Antigen in Prostate Cancer DiagnosisLein M.a · Lein M.a · Jung K.a · Jung K.a · Elgeti U.a · Elgeti U.a · Petras T.a · Petras T.a · Stephan C.a · Stephan C.a · Brux B.b · Brux B.b · Sinha P.b · Sinha P.b · Winkelmann B.a · Winkelmann B.a · Schnorr D.a · Schnorr D.a · Loening S.A.a · Loening S.A.a
aDepartment of Urology and bInstitute of Laboratory Medicine and Pathobiochemistry, University Hospital Charité, Humboldt University, Berlin, Germany
Objective: To evaluate the diagnostic utility of free prostate specific antigen (fPSA), alpha–1– antichymotrypsin–bound PSA (PSA–ACT), complexed PSA (cPSA), and including their associated ratios to total PSA (tPSA) in serum for discrimination between prostate cancer (PCa) and benign prostatic hyperplasia (BPH). Methods: A total of 166 white men (age: 65–88 years) with a tPSA between 2 and 20 µg/l were retrospectively analysed. Serum concentrations of tPSA, fPSA, PSA–ACT and cPSA were measured in 118 untreated PCa patients and 48 patients with BPH. The tPSA and cPSA concentrations were measured with the Bayer Immuno 1 system (Bayer Diagnostics, Tarrytown, USA). The Elecsys system 2010 (Roche Diagnostics, Mannheim, Germany) was used for determination of tPSA and fPSA. The PSA–ACT assay is a newly, developed prototype assay on the ES system (Roche Diagnostics, Mannheim, Germany). Results: For statistical analysis only patients with tPSA between 2 and 20 µg/l were enrolled. The median concentrations of tPSA (Bayer: PCa 7.36 µg/l, BPH 4.03 µg/l; Roche: PCa 7.75, BPH 4.13), PSA–ACT (PCa 6.98, BPH 3.18) and cPSA (PCa 6.46, BPH 3.20) were significantly different. The median ratios of fPSA/tPSA (PCa 12.8 vs. BPH 22.4%), PSA–ACT/tPSA (PCa 89.8 vs. BPH 76.1%) and cPSA/tPSA (PCa 90.5 vs. BPH 81.7%) were significantly different between PCa and BPH patients. Using the areas under the curves, receiver operating characteristics analysis (tPSA: 2–20 µg/l) for discrimination between PCa and BPH showed that the ratios fPSA/tPSA (area under the curve: 0.77), PSA–ACT/tPSA (0.72) and cPSA/tPSA (0.78) were significantly different from tPSA (Bayer: 0.53; Roche: 0.55). PSA–ACT (0.64) and cPSA (0.59) alone were not significantly different from tPSA. The calculated ratios fPSA/tPSA, PSA–ACT/tPSA and cPSA/tPSA were not significantly different. Conclusion: The determination of PSA–ACT or cPSA and the associated ratios do not improve the diagnostic impact to discriminate between PCa and BPH compared to fPSA/tPSA ratio. The ratios PSA–ACT/tPSA or cPSA/tPSA can be considered to be alternative tools of fPSA/tPSA.