RATIO OF FREE-TO-TOTAL PROSTATE-SPECIFIC ANTIGEN IN SERUM CANNOT DISTINGUISH PATIENTS WITH PROSTATE-CANCER FROM THOSE WITH CHRONIC INFLAMMATION OF THE PROSTATE

Purpose: We demonstrate the effect of chronic inflammation of the pros tate on the ratio of free-to-total prostate specific antigen (PSA) in serum calculated as a percentage of free PSA and, therefore, that perc entage of free PSA is an unspecific means to distinguish among prostat e cancer, chronic prostatitis and benign prostatic hyperplasia (BPH). Materials and Methods: Total, free and percentage of free PSA was meas ured in 66 men with prostate cancer, 119 with BPH and 17 with asymptom atic chronic prostatitis. In all patients the diagnosis was histopatho logically confirmed by microscopic examination of prostatic specimens after sextant biopsy, transurethral prostatic resection or prostatecto my. Results: The median values of total, free and percentage of free P SA were 4.11 mu g./l., 0.75 mu g./l. and 20.4% in patients with BPH, 1 0.0 mu g./l., 0.84 mu g./l. and 8.5% in those with prostate cancer, an d 7.60 mu g./l., 1.23 mu g./l. and 10.6% in those with chronic prostat itis. Patients with prostate cancer and chronic prostatitis had a sign ificantly lower percentage of free PSA than those with BPH. Receiver o perating characteristics curve analysis showed that percentage of free PSA as a discriminator between prostate cancer and BPH was not suitab le for differentiating between prostate cancer and chronic prostatitis . Conclusions: Chronic prostatitis is not characterized by elevated to tal PSA concentrations alone but also by a decreased percentage of fre e PSA, a tendency similar to that in prostate cancer. This unspecific change in percentage of free PSA must be considered to interpret the p ercentage of free PSA correctly.