Serum testosterone improves the accuracy of Prostate Health Index for the detection of prostate cancer

Abstract

ObjectiveProstate cancer (PCa) detection suffers from low specificity when using the prostate-specific antigen (PSA) alone. The aim of this study was to investigate the applicability of total testosterone (tT), free testosterone (fT), the fraction (%) of fT to tT (%fT), and bioavailable testosterone (bioT) in serum to improve the diagnostic validity of the serum (−2)pro-PSA-based Prostate Health Index (PHI). Design and methodsTotal and free PSA (tPSA, fPSA), (−2)pro-PSA, testosterone, and sex-hormone-binding globulin were measured by automated immunoassays from serum of 193 men scheduled for prostate biopsy (99 PCa, 94 without PCa). fT and bioT were calculated using an online calculator. Statistical analyses were performed by non-parametric tests (Wilcoxon signed rank, Mann–Whitney, Kruskal–Wallis), binary logistic regression, and receiver operating characteristic (ROC) analyses. ResultsCompared with the non-malignant controls, PCa patients had significantly higher tPSA concentrations and PHI values, but lower %fPSA values and lower concentrations of tT, fT, and bioT. PCa could be differentiated from controls by PHI, tT, fT, bioT, and %fPSA. PHI showed the largest area under the ROC curve (AUC=0.73) that was increased further by the inclusion of bioT or tT in a binary logistic regression model. The AUC of PHI in patients with tT concentrations of <8nmol/L (indicating biochemical hypogonadism) was significantly larger than that in patients with higher tT values (0.86 vs. 0.70; P=0.024). ConclusionsThe PHI-based discrimination between PCa patients and non-malignant controls could be improved by the simultaneous determination of testosterone. Patients with testosterone concentrations of <8nmol/L have the greatest benefit.