Discriminatory Ability of Prostate Specific Antigen -Derived Indices in Differentiating Prostate Cancer from Benign Prostatic Hyperplasia

Background: Prostate-specific antigen (PSA) is widely used to distinguish prostate cancer from benign conditions, but its limited specificity often results in unnecessary biopsies.To improve diagnostic performance, various PSA-derived indices have been developed, including free PSA (fPSA), the free-to-total PSA ratio (f/t PSA), PSA density, PSA transition zone density (PSA TZ density), and fPSA density.This study aimed to compare the discriminatory ability of PSA and PSA-derived indices, including fPSA TZ density, for differentiating prostate cancer from benign prostatic hyperplasia (BPH).Methods: We retrospectively reviewed 326 Korean men who underwent PSA, fPSA, transrectal ultrasonography, and prostate biopsy at Nowon Eulji Medical Center between January 2016 and June 2024.All cases were biopsy-confirmed.The discriminatory ability of PSA and PSA-derived indices for distinguishing prostate cancer from BPH was assessed.Results: In the overall biopsy-confirmed study population, PSA, PSA density, and PSA TZ density performed best.PSA showed the highest AUC (0.789), followed by PSA TZ density (0.759) and PSA density (0.745).In men aged ≥ 70 years, f/t PSA showed the highest specificity (95.8%).Within the PSA gray zone (4-10 ng/mL), f/t PSA yielded the highest discriminatory ability (AUC 0.714), supporting its use in biopsy decision-making.Stage-stratified analyses showed stage-specific differences in AUC values, with higher values observed in advanced-stage disease.Conclusions: Among PSA-derived indices, PSA, PSA density, and PSA TZ density provided the best overall accuracy, and f/t PSA was most valuable in the PSA gray zone and in older age groups.These findings support individualized interpretation of PSA indices according to age, PSA interval, and disease stage.