Comparison of the percent free prostate-specific antigen levels in the serum of healthy men and in men with recurrent prostate cancer after radical prostatectomy

The percentage of free PSA in serum is currently used to better discriminat e between patients with prostate cancer and patients with benign prostatic hyperplasia, in prostate cancer screening programs. We measured using non-c ompetitive immunological techniques, the total PSA and free PSA in post-sur gical serum of prostate cancer patients who underwent radical prostatectomy and then relapsed. We compared these data with those of a group of 40 age- matched men with no evidence of prostatic disease. Although in general, pat ients with prostate cancer had lower percentage of free PSA in serum in com parison to the controls, a subset of these patients (approximately 20%) had percent free PSA significantly higher than the levels considered as exclus ive of prostate cancer in screening programs. We also found that percent fr ee PSA does not correlate significantly with most of the standard clinical or pathological indicators of prostate cancer aggressiveness. Only a weak n egative association with Gleason Score was observed. The percent free PSA i n serum of relapsing prostate cancer patients varies within a relatively wi de range and does not correlate significantly with indicators of cancer agg ressiveness. The use of percent free PSA for excluding prostate cancer in s creening programs must be approached with caution until the mechanism of lo w percent free PSA in the majority but not all prostate cancer patients is elucidated. (C) 2000 Elsevier Science B.V. All rights reserved.