The clinical utility of measuring free-to-total prostate-specific antigen (PSA) ratio and PSA density in differentiating between benign prostatic hyperplasia and prostate cancer

OBJECTIVE: To evaluate the role of free-to-total prostate-specific antigen ratio (f/tPSA), prostate volume and PSA density in differentiating between men with prostate cancer and benign prostatic hyperplasia (BPH). PATIENTS AND METHODS: The study comprised 51 patients who were assessed after transurethral electroresection of the prostate (16 with prostate cancer and 35 with BPH). Patients with a tPSA of < or = 4.0 ng/mL and > or = 30.0 ng/mL were excluded from the analysis. Total and fPSA were measured using an immunoradiometric assay and prostate volume was determined by transrectal ultrasonography. The incidence of prostate cancer and BPH was then compared with the PSA variables to determine specificity and predictive value. RESULTS: Most patients with BPH had a tPSA of 4.0-6.0 ng/mL; no patients with BPH had a tPSA of > 20.0 ng/mL. Most patients with prostate cancer had a f/tPSA of 6-10%. The area under the receiver operating characteristic curve for f/tPSA was significantly greater than that for tPSA (P < 0.003). CONCLUSIONS: The measurement of f/tPSA and PSA density increase the specificity of the differential diagnosis between BPH and prostate cancer.