A multicenter clinical trial on the use of alpha 1 ‐antichymotrypsin‐prostate‐specific antigen in prostate cancer diagnosis

BACKGROUND The aim was to evaluate the clinical performance of alpha 1 ‐antichymotrypsin prostate‐specific antigen (PSA‐ACT) for early diagnosis of prostate cancer (PCa) in a multicenter trial. METHODS Three hundred sixty‐seven white men with PCa and 290 with benign prostatic hyperplasia (BPH) with tPSA concentrations between 2 and 20 μg/L were analyzed. The Elecsys system 2010 (Roche Diagnostics, Germany) was used for determination of total PSA (tPSA) and free PSA (fPSA). The PSA‐ACT test was a prototype assay used on the ES system (Roche Diagnostics). RESULTS The median concentrations of tPSA (PCa: 8.43 μg/L vs. BPH: 6.60 μg/L) and PSA‐ACT (8.30 μg/L vs. 6.46 μg/L) were significantly different, respectively. The median ratios of fPSA/tPSA (PCa: 12% vs. BPH: 16%) and PSA‐ACT/tPSA (98% vs. 95%) were significantly different. Receiver operating characteristics (ROC) analysis for discrimination between PCa and BPH (tPSA between 2 and 20 μg/L) was performed with 252 matched pairs and showed that the area under the curve (AUC) of the ratio fPSA/tPSA (0.66) was significantly different from tPSA (0.50) and PSA‐ACT (0.52). PSA‐ACT alone or the ratio PSA‐ACT/tPSA (0.56) were not significantly different from tPSA. For tPSA between 4 and 10 μg/L (n = 145 pairs), the AUC of the ratio fPSA/tPSA (0.65) was significantly higher than tPSA (0.50) and PSA‐ACT (0.54). Significant differences between tPSA and PSA‐ACT or PSA‐ACT/tPSA (0.56) were not found. CONCLUSIONS The determination of PSA‐ACT as well as the PSA‐ACT/tPSA ratio did not improve the diagnostic impact in patients undergoing evaluation for PCa compared to fPSA/tPSA ratio. Prostate 47:77–84, 2001. © 2001 Wiley‐Liss, Inc.