THE VALUE OF THE RATIO OF FREE-TO-TOTAL PROSTATE-SPECIFIC ANTIGEN FORSTAGING PURPOSES IN PREVIOUSLY UNTREATED PROSTATE-CANCER

Purpose: We analyzed the use of the ratio of free-to-total prostate sp ecific antigen (PSA), also termed percentage of free PSA, for predicti ng tumor stage, volume and grade in patients with clinically localized prostate cancer. Materials and Methods: A total of 515 consecutive pa tients underwent further prostate evaluation due to elevated PSA (grea ter than 4.0 ng./ml.) or abnormal digital rectal examination. Prostate cancer was diagnosed in 307 patients (59.6%), including 170 (55.4%) w ho underwent radical retropubic prostatectomy. Data on pathological st age, Gleason grade, and total and Gleason grade 4 cancer volume were a vailable in all patients. In the remaining 208 men (40.4%) benign pros tate hyperplasia was diagnosed. Total and free PSA was measured in pre operative serum. Results: Total PSA was significantly higher (p <0.000 1) in the 71 men with stage pT3 tumors than in the 91 with pT2 disease . Eight patients had stage pT4 tumors. Cancer volume correlated well w ith advancing pathological stage (p <0.0001) and total PSA (p <0.0001) . The free-to-total PSA ratio was not significantly different (p = 0.9 3) in stages pT2 and pT3 tumors, and it did not correlate with total ( p = 0.71) or pure Gleason grade 4 (p = 0.94) cancer volume. However, t he ratio of free-to-total PSA tended to decrease (p = 0.07) in tumors of increasing Gleason grade. Conclusions: The ratio of free-to-total P SA does not help in the preoperative prediction of final tumor stage a nd volume. However, disease grading may alter the free-to-total PSA ra tio.