Free PSA in the detection of prostatic carcinoma

A new possibility for improved differentiation between malignant and benign prostatic disease is the determination of free-PSA in the indifferent grey area of total PSA between 2 and 30 ng/ml. In a retrospective study of 106 men with a total PSA between 2 and 30 ng/ml we studied the ratio of free to total PSA. The differentiation between prostatic carcinoma (PCa) and benign prostatic hyperplasia (BPH) was verified by randomised biopsies. PSA was measured with Tandem-E, Hybritech, USA and free-PSA with Tandem-R, Hybritech, USA and Immunite-R, DPC-Biermann, USA. Patients (pts.) with an untreated, virgin PCa releaved a highest quotient free-PSA/PSA lower than 0.25. The highest quotient in pts. with treated PCa was 0.51 and in pts with BPH was 0.52. Therapy of PCa with LHRH-analogues changed free-PSA toward a BPH-profile. Both kits used for free-PSA gave similar results. Our study suggests, that every free-PSA higher than 25% of PSA should not be a valuable, supplementary parameter for pts. with unclear diagnosis.