Ratio of alpha1-antichymotrypsin - Prostate specific antigen to total prostate specific antigen in prostate cancer diagnosis

Objective: To evaluate the analytical performance and diagnostic utility of prostate specific antigen (PSA) bound to alpha1-antichymotrypsin (ACT) in serum to improve the differentiation between benign prostatic hyperplasia ( BPH) and prostate cancer. (PCa). Methods: A total of 351 white men 21 to 88 years old were analysed. Serum concentration of tPSA, free PSA (fPSA) and ACT-PSA were measured in 163 untreated PCa patients (median age 66 years), 94 patients with histologically of clinically confirmed BPH (median age 65 years) and 94 men without prostate disease considered as controls (median a ge 54 years). The Elecsys system 2010 (Roche Diagnostics, Germany) was used for the determinations of tPSA and fPSA. The ACT-PSA assay is a new develo ped prototype on the ES system (Roche Diagnostics Germany). Results: The AC T-PSA assay showed reliable data of analytical performance in comparison to established assays for tPSA and fPSA. The median concentrations of tPSA (P Ca: 9.22 mug/L, BPH: 2.28 mug/L, controls: 0.99 mug/L) and ACT-PSA (7.99 mu g/L vs. 1.63 mug/L vs. 0.58 mug/L) were significantly different, respective ly. The median ratios of fPSA/tPSA (PCa: 12.3%, BPH: 25.4%), ACT PSA/tPSA ( 90.5% vs. 66.6%) and fPSA/ACT-PSA (14.0% vs. 35.6%) were significantly diff erent between PCa and BPH patients. Significant differences of ratios betwe en BPH and controls were not observed. Receiver operating characteristics a nalysis (tPSA up to 20 mug/L) for discrimination between PCa and BPH showed that the ratios fPSA/tPSA (area under the crave: 0.861) and fPSA/ACT-PSA ( 0.847) were significantly different from tPSA (0.663), but ACT-PSA (0.733) alone and also the ratio of ACT-PSA/tPSA (0.780) were not significantly dif ferent from tPSA (0.663). Conclusion: The ratio fPSA/tPSA showed the best d iscrimination between BPH and PCa. The single or. additional determination of ACT-PSA to tPSA does not improve the differentiation between the two gro ups of patients.