Prostate-specific antigen adjusted for the transition zone volume versus free-to-total prostate-specific antigen ratio in predicting prostate cancer

Background: We performed this study to assess the efficacy of prostate-specific antigen adjusted for the transition zone volume (PSATZ) and free-to-total prostate-specific antigen (PSA) ratio (F/T ratio) in predicting prostate cancer in men with intermediate PSA levels of 4.1-10.0 ng/mL. Methods: Between March 1997 and September 1998, PSATZ was obtained from 67 patients who underwent ultrasonography guided systemic sextant biopsies and had a PSA of 4.1-10.0 ng/mL. PSATZ was compared with F/T ratio via receiver operating characteristic (ROC) curves. Results: Of 67 patients, 22 (32.8%) had prostate cancer and 45 (67.2%) had benign prostatic hyperplasia (BPH) on pathologic examination. Mean PSA, PSA density, F/T ratio and PSATZ were 7.96 ± 2.01 ng/mL, 0.28 ± 0.14 ng/mL/cc, 0.10 ± 0.06 and 0.70 ± 0.28 ng/mL/cc in patients with prostate cancer and 6.39 ± 1.68 ng/mL, 0.16 ± 0.06 ng/mL/cc, 0.15 ± 0.05 and 0.29 ± 0.10 ng/mL/cc in patients with BPH, respectively. The ROC curve analysis demonstrated that PSATZ predicted the biopsy outcome significantly better than F/T ratio in all 67 patients (P < 0.01) and in a subset of 53 men with normal digital rectal examination (P < 0.01). With a cut-off value of 0.35 ng/mL/cc, PSATZ had a sensitivity of 86% and a specificity of 89% for predicting prostate cancer. Conclusions: These results suggest that PSATZ and F/T ratio may be useful in diagnosing prostate cancer with intermediate levels of PSA. Prostate-specific antigen adjusted for the transition zone volume is more accurate than F/T ratio in distinguishing benign prostatic disease from prostate cancer. But large prospective studies are required to assess the precise role of PSATZ and F/T ratio in early prostate cancer detection.