Diagnostic Role of Serum Free-to-Total Prostate Specific Antigen (PSA) Ratio in Prostate Cancer with Serum Total Concentration of PSA below 4 ng/mL.

PURPOSE: To examine the effectiveness of serum free-to-total prostate specific antigen ratio (%fPSA) for the detection of prostate cancer (PCa) in men with different serum total PSA (tPSA) categories. MATERIALS AND METHODS: From January 2010 to December 2013, a total of 225 patients with lower urinary tract symptoms (LUTS) underwent tPSA and %fPSA measurements. Histological examination with calculation of Gleason score and whole body bone scans were performed in identified cases of PCa. RESULTS: PCa was diagnosed in 44 (19.6%) patients and the remaining 181 patients had benign prostate disease. PCa was detected in 5 (23.8%), 13 (8.7%) and 26 (47.3%) cases with tPSA level ranges≤4 ng/ml, 4 to 10 ng/ml and >10 ng/ml, respectively. The average Gleason score was 7.2±0.2. Some 6 (13.6%) out of 44 PCa patients had bone metastases. The sensitivity was 80% and specificity was 81.3% at the cut-off %fPSA of 15% in PCa patients with a tPSA level below 4 ng/ mL. A lower %fPSA was associated with PCa patients with Gleason score≥7 than those with Gleason score≤6 (11.7±0.98 vs. 16.5±2.25%, P=0.029). No obvious relation of %fPSA to the incidence of bone metastasis was apparent in this study. CONCLUSIONS: The clinical application of %fPSA could help to discriminate PCa from benign prostate disease in men with a tPSA concentration below 4 ng/mL.