ACT-PSA and complexed PSA elimination kinetics in serum after radical retropubic prostatectomy: Proof of new complex forming of PSA after release into circulation

Objectives. To study the elimination kinetics of alpha(1)-antichymotrypsin (ACT)-prostate-specific antigen (PSA) and complexed PSA (cPSA) in compariso n to the biexponential decrease of total PSA and free PSA after radical pro statectomy. Methods. Serum total PSA, free PSA, ACT-PSA, and cPSA values and the corres ponding ratios were determined in venous blood from 12 patients with prosta te cancer. The samples were taken before surgery, immediately after surgery , 1, 2, 3, 4, 5, and 6 hours after surgery, and then once daily for the nex t 10 days. Total PSA and cPSA were analyzed by using Immune 1 PSA assays (B ayer Corporation); free PSA was measured using the AxSym test kit (Abbott D iagnostics). For ACT-PSA, the ES analyzer system was used (Roche Diagnostic s). Statistical calculations were performed with the analysis of variance a nd Wilcoxon tests. Results. During the first 6 hours after radical retropubic prostatectomy, w e found nearly constant levels of ACT-PSA and cPSA, in contrast to the rapi d elimination of free PSA and significant decrease in total PSA. From days 1 to 10, a continuous and nearly identical decrease of ACT-PSA and cPSA occ urred compared with total PSA; free PSA was eliminated more rapidly. Conclusions. In addition to the opinion that the first PSA decrease might b e an effect of the operation itself or caused by renal elimination alone, o ur findings indicate that the initial rapid decrease of free PSA immediatel y after surgery could be caused by new complex forming of PSA with ACT and other serum protease inhibitors. UROLOGY 55: 560-563, 2000. (C) 2000, Elsev ier Science Inc.