Prostate-specific antigen adjusted for the transition zone volume as a second screening test: A prospective study of 248 cases

AIM: This study was conducted to verify the effectiveness of prostate-specific antigen adjusted for the transition zone volume (PSATZ), and its availability as a second screening test for prostate cancer detection. MATERIALS AND METHODS: Total prostate-specific antigen (PSA) and free PSA was measured in male patients who visited our outpatient department for voiding difficulty or screening for prostate cancer. Patients who had an intermediate PSA level between 4.0 and 10.0 ng/mL, with an apparently normal prostate on a digital rectal examination, were enrolled. PSATZ, free-to-total PSA ratio (F/T ratio) and PSA density (PSAD) were calculated and statistical comparisons between biopsy-positive (cancer) and biopsy-negative patients (benign) were conducted. RESULTS: Of 248 patients, 51 (20.6%) had prostate cancer and 197 (79.4%) had benign prostatic hyperplasia (BPH) on pathologic examination. Mean PSA, PSAD, F/T ratio and PSATZ were 7.48 +/- 1.77 ng/mL, 0.23 +/- 0.09 ng/mL per mL, 0.14 +/- 0.08 and 0.71 +/- 0.44 ng/mL per mL in patients with prostate cancer and 6.59 +/- 1.60 ng/mL, 0.16 +/- 0.07 ng/mL per mL, 0.21 +/- 0.11 and 0.36 +/- 0.30 ng/mL per mL in patients with benign, respectively. Receiver operating characteristics (ROC) curve analysis demonstrated that PSATZ predicted the biopsy outcome better than F/T ratio. With a cut-off value of 0.37 ng/mL per mL, PSATZ had a sensitivity of 74.5% and a specificity of 72.6% for predicting prostate cancer. The maximal cut-off value that preserves 100% of sensitivity was 0.2, and at this cut-off value, 16.1% of unnecessary biopsies could be reduced. CONCLUSIONS: Prostate-specific antigen adjusted for the transition zone volume may be more useful than other strategies in detecting prostate cancer in patients with intermediate PSA levels of 4.0-10.0 ng/mL. It can be used as a second screening test to reduce unnecessary biopsy.