FREE TO TOTAL PROSTATE-SPECIFIC ANTIGEN (PSA) RATIO IS SUPERIOR TO TOTAL-PSA IN DIFFERENTIATING BENIGN PROSTATE HYPERTROPHY FROM PROSTATE-CANCER

BACKGROUND. Serum prostate-specific antigen (PSA) exists in different molecular forms, and their respective concentration has been proposed as a useful tool to improve discrimination between benign prostatic hy pertrophy (BPH) and prostate cancer (PC). METHODS. The relevance of th e free to total PSA ratio was prospectively studied in a selected urol ogy clinic population of 420 patients. Total serum PSA ranged from 2.1 to 30 ng/ml; 154 had PC and 266 had BPH. RESULTS. Receiver operating characteristic (ROC) curves were constructed for the total population (total-PSA range from 2.1 to 30 ng/ml) and for the diagnostic gray zon e of 2.1-10 ng/ml. For the two groups, the free to total PSA ratio had a higher specificity than total-PSA for all sensitivity levels. Cut-o ff values were found to vary with prostate weight. CONCLUSIONS. Althou gh free to total PSA ratio demonstrated better performances than total -PSA, its use in screening appears problematic, due to the low prevale nce of prostate cancer. (C) 1996 Wiley-Liss, Inc.