EVALUATION OF PATIENTS WITH DISEASES OF THE PROSTATE USING PROSTATE-SPECIFIC ANTIGEN DENSITY

Objective To compare the efficacy of two tests, prostatic-specific ant igen (PSA) and the PSA/prostate volume ratio (PSAD), as diagnostic and staging markers to discriminate patients with benign prostatic hyperp lasia (BPH) from patients with cancer of the prostate (CaP). Patients and methods Prostate gland volumes were estimated in 60 patients with BPH and 88 patients with clinically organ-confined CaP by performing t ransrectal ultrasonography (TRUS) and using the prolate ellipse formul a. Serum PSA concentration was determined using an enzyme immunoassay. In patients with BPH, the prostates were removed either by transureth ral resection or retropubic prostatectomy. Patients with CaP underwent laparoscopic pelvic lymphadenectomy followed by radical perineal pros tatectomy. PSAD was calculated by relating the serum PSA level to the TRUS-estimated prostate volume. Results The median PSA level was 4.4 n g/mL in patients with BPH, 9.3 ng/mL in patients with CaP-NO disease a nd 24 ng/mL in those with CaP-N+ disease. However, imposing a PSA limi t of 4 ng/mL for the diagnosis of CaP gave a positive predictive value of only 64.8%, whereas a limit of 10 ng/mL gave a positive predictive value of 71.4%. In contrast, the median PSAD was 0.086 ng/mL/cm(3) in patients with BPH, but was 0.295 ng/mL/cm(3) in patients with NO-dise ase and 0.775 ng/mL/cm(3) in those with N+-disease. With a limit of 0. 15 ng/mL/cm(3) the positive predictive value of PSAD was 81%. Furtherm ore, a limit of 0.6 ng/mL/cm(3) revealed a positive predictive value o f 81% for the diagnosis of metastatic lymph node involvement. Conclusi ons There was a considerable overlap of PSA concentrations in patients with BPH and CaP, and PSA was not sufficiently accurate to distinguis h between them. In contrast, PSAD enhanced the discrimination between BPH and CaP and may provide additional information about the status of the lymph nodes in patients with CaP.