A prospective trial in evaluating role of percent free PSA in prostatic pathology

INTRODUCTION AND OBJECTIVE The percentage of free prostate-specific antigen (PSA) in serum has been shown to enhance the specificity of PSA testing for prostate cancer detection, but earlier studies provided only preliminary cutoffs for clinical use. To develop risk assessment guidelines and a cutoff value for defining abnormal percentage of free PSA in a population of men to whom the test would be applied. METHODS: A total of 100 men, 40-75 years of age with a palpably benign prostate gland, PSA of 4.0-10ng/ml and histologically confirmed diagnosis, all subjects had undergone ultrasound-guided 6-sector needle biopsies of the prostate and, thus, had a histologically confirmed diagnosis prior to determination of free PSA concentrations. Mean values were compared with t-tests (chi-sqare test, fischer exact test) for normally distributed parameters and the Mann-Whitney U test for non-normal parameters., and linear regression analysis was used to assess the relationships among percentage of free PSA and PSA Results.-The percentage of free PSA used in 2 ways: as a single cutoff (ie, perform a biopsy for all patients at or below a cutoff of 10% free PSA) or as an individual patient risk assessment The 10% free PSA cutoff detected 95% of cancers while avoiding 20% of unnecessary biopsies. The cancers associated with greater than 10% free PSA were more prevalent in older patients, and generally were less threatening in terms of tumor grade. For individual patients, a lower percentage of free PSA was associated with a higher risk of cancer (range, 8%-56%). Conclusions-Use of the percentage of free PSA can reduce unnecessary biopsies in patients undergoing evaluation for prostate cancer, with a minimal loss in sensitivity in detecting cancer. A cutoff of 10% or less free PSA is recommended for patients with PSA values between 4.0 and 10.0 ng/mL and a palpably benign gland, regardless of patient age or prostate size. Key words-PSA-prostate specific antigen, prostate cancer.