ANALYSIS OF PERCENT FREE PROSTATE-SPECIFIC ANTIGEN (PSA) FOR PROSTATE-CANCER DETECTION - INFLUENCE OF TOTAL PSA, PROSTATE VOLUME, AND AGE

Objectives. To determine whether the use of the free-to-total PSA rati o (percent free PSA) could increase the specificity of PSA testing for prostate cancer detection in men with serum PSA concentrations betwee n 4.0 and 10.0 ng/mL, and to assess the influence of total PSA, prosta te volume, and age on percent free PSA. Methods. Sera were obtained fr om 217 men with histologically confirmed diagnoses (139 prostate cance r, 78 benign). Free and total PSA concentrations were determined using Hybritech Tandem(R) assays. Results. Use of percent free PSA increase d PSA specificity: 29% of negative biopsies would be spared while reta ining 95% sensitivity. Percent free PSA increased with increasing age and prostate volume. Percent free PSA decreased as total PSA increased . A significant relation exists between percent free PSA and the proba bility of a positive biopsy; in this cohort, a patient with a low perc ent free PSA (less than or equal to 10%) had a higher probability of c ancer (63 +/- 9%) than a patient with a high percent free PSA (greater than or equal to 26%) (probability 2 +/- 3%). Conclusions. Percent fr ee PSA may be used as an aid in distinguishing prostate cancer from be nign disease in men with a total PSA between 4.0 and 10.0 ng/mL. Large prospective multicenter trials are required to develop consistent rec ommendations and determine the appropriate cutpoints and risk probabil ities, controlling trolling for total PSA, prostate volume, age, and b iopsy history. Copyright 1996 by Elsevier Science Inc.