SERUM-FREE TOTAL PROSTATIC-SPECIFIC ANTIGEN IN PROSTATE-CANCER PATIENTS TREATED WITH LH-RH AGONISTS

Objective: This study is based on promising results using the ratio of free/ total (F/T) prostatic-specific antigen (PSA) for discrimination between benign prostatic hypertrophy and prostate cancer. We tried to determine the value of F/T PSA in different clinical situations at a certain time point during followup of luteinizing-hormone-releasing ho rmone (LH-RH) agonist treatment and to correlate it to T-PSA. Patients and Methods: 182 patients followed-up for different periods in the la st 3 years were routinely monitored for serum T-PSA. During the last 1 1 months, F-PSA was also measured together with T-PSA, and the ratio o f F/T PSA was calculated. In 26 patients, the ratio of F/T PSA was mon itored sequentially in several samples. Results: Although 5 patterns o f clinical response to LH-RH agonists were identified according to pre vious T-PSA, the F/T ratio could significantly (p < 0.05) discriminate between patients responding to treatment in contrast to patients esca ping, fluctuating or not responding to hormonal ablation. Those patien ts responding to hormones showed a higher F/T PSA ratio (36.5 +/- 33.1 %) compared to the nonresponding group (12.0 +/- 10.1%). Conclusions: During individual follow-ups, the pattern of response to LH-RH treatme nt is reflected by the F/T PSA ratio: while successful treatment cause s an F/T PSA increase, relapse is accompanied by a decrease in this ra tio. However, the changes in the F/T PSA ratio did not precede the ind icative changes in T-PSA. It seems that increased values of F/T PSA ra tios are intrinsic features of 'benign' prostatic disease, and the mol ecular events resulting in different PSA molecules in various clinical situations have to be elucidated.