The value of percentage free prostate specific antigen (PSA) in the detection of prostate cancer among patients with intermediate levels of total PSA (4.0-10.0 ng/mL) in Nigeria

Objectives: To assess the value of percentage free prostate-specific antigen (% fPSA) in the detection of prostate cancer among Nigerian men with an intermediate total PSA level (4-10 ng/mL), and to show if the optimum threshold for biopsy is different from Caucasian values when the widely used (six-core, digitally directed) prostate biopsy protocol in Nigerians is applied. Patients and methods: The study included 105 patients aged > 50 years, with a palpably benign prostate gland and intermediate levels of total PSA (4-10 ng/mL). These patients had a free PSA assay and a transrectal digitally directed six-core biopsy of the prostate. The % fPSA was calculated and the optimum threshold value for detecting prostate cancer was determined. Results: The mean (SD) age of the patients was 64.4 (6.6) years and their mean (SD) total PSA level was 6.6 (1.7) ng/mL. Of these men 14 (13.3%) had cancer of the prostate detected by the prostate biopsy. The % fPSA level related directly to sensitivity values but inversely to the specificity and the positive predictive values. The best threshold of % fPSA for detecting cancer in these men was < 40%, with a sensitivity of 100%, specificity of 93.4% and a positive predictive value of 70% (P<0.05). Conclusions: In evaluating Nigerian patients with a palpably benign prostate gland and within the intermediate total PSA range, when digitally directed biopsy protocol is adopted, a % fPSA threshold of < 40% will detect significant percentage of those with prostate cancer, with a minimal number of unnecessary biopsies. This value differs from that reported in western studies in which transrectal ultrasonography-directed biopsy was used. (C) 2012 Arab Association of Urology. Production and hosting by Elsevier B.V. All rights reserved.