Comparison of percent free PSA, PSA density, and age-specific PSA cutoffs for prostate cancer detection and staging

Objectives. Various methods have been proposed to increase the specificity of prostate-specific antigen (PSA), including age-specific PSA reference ra nges, PSA density (PSAD), and percent free PSA (%fPSA). In this multicenter study, we compared these methods for their utility in cancer detection and their ability to predict pathologic stage after radical prostatectomy in p atients with clinically localized, Stage T1c cancer. Methods. Seven hundred seventy-three men (379 with prostate cancer, 394 wit h benign prostatic disease), 50 to 75 years old, from seven medical centers were enrolled in this prospective blinded study. All subjects had a palpab ly benign prostate, PSA 4.0 to 10.0 ng/mL, and a histologically confirmed d iagnosis. Hybritech's Tandem PSA and free PSA assays were used. Results. %fPSA and age-specific PSA cutoffs enhanced PSA specificity for ca ncer detection, but %fPSA maintained significantly higher sensitivities. Ag e-specific PSA cutoffs missed 20% to 60% of cancers in men older than 60 ye ars of age. %fPSA and PSAD performed equally well for detection (95% sensit ivity) if cutoffs of 25% fPSA or 0.078 PSAD were used. The commonly used PS AD cutoff of 0.15 detected only 59% of cancers. %fPSA and PSAD also produce d similar results for prediction of the post-radical prostatectomy patholog ic stage. Patients with cancer with higher %fPSA values (greater than 15%) or lower PSAD values (0.15 or less) tended to have less aggressive disease. Conclusions. The results of this study demonstrated that cancer detection ( sensitivity) is significantly higher with %fPSA than with age-specific PSA reference ranges. %fPSA and PSAD provide comparable results, suggesting tha t %fPSA may be used in place of PSAD for biopsy decisions and in algorithms for prediction of less aggressive tumors since the determination of %fPSA does not require ultrasound. UROLOGY 56: 255-260, 2000. (C) 2000, Elsevier Science Inc.