Diagnostic value of free prostate-specific antigen among men with a prostate-specific antigen level of <3.0 μg per liter

Objectives: The percentage of free prostate-specific antigen (%fPSA) improves the diagnostic accuracy for prostate cancer when the serum level of total PSA (tPSA) is elevated. Approximately 14% of men with a tPSA below 3 mu g/l have prostate cancer on biopsy, but the diagnostic value of %fPSA in such men is rather unknown. The purpose was to estimate the impact of %fPSA on future prostate cancer risk among men with a normal tPSA in prostate cancer screening. Subjects and methods: The first round of the Finnish arm of the European Randomized Trial for Screening of Prostate Cancer in 1996 to 1999 comprised 20,793 men aged 55-67 yr. Screen-negative men (tPSA level below 3.0 mu g/l, n = 17,680) were followed up until the end of 2003. Cumulative risk of prostate cancer was calculated as a function of %fPSA. Results: During the median follow-up of 5.8 yr (range, 0-7.7 yr), 327 men were diagnosed with prostate cancer and 25% of them had a Gleason score of 7 or higher. Five years after the first screening, cumulative risk of prostate cancer was 1.7% (95%CI, 1.5-1.9%). Men with a %fPSA in the lowest quartile (<14.2%) showed a 6.9-fold risk compared with those with a level in the highest quartile (>23.7%). Conclusions: In men with a low serum tPSA, a low %fPSA is a strong predictor of later diagnosis of prostate cancer. (C) 2007 European Association of Urology. Published by Elsevier B.V. All rights reserved.