Clinical value of human glandular kallikrein 2 and free and total prostate-specific antigen in serum from a population of men with prostate-specific antigen levels 3.0 ng/mL or greater

Objectives. To investigate the clinical value of human glandular kallikrein 2 (hK2) compared with free (f) and total (t) prostate-specific antigen (PS A) in the early detection of prostate cancer (PCa). Methods. In PCa screening conducted in 1995 to 1996 in Goteborg, Sweden, 58 53 of 9811 randomly selected men (aged 50 to 66 years; median 61) accepted PSA testing; those with tPSA levels of 3.0 ng/mL or greater were offered di gital rectal examination, transrectal ultrasound, and sextant biopsies. Ser um from 604 of 611 biopsied men (18% with positive digital rectal examinati ons, tPSA range 3.0 to 220 ng/mL, 144 men with PCa) was analyzed for hK2 (r esearch assay) and tPSA and fPSA (Prostatus). Sera were stored at -20 degre es C for a maximum of 2 weeks for tPSA and fPSA and 3 years for hK2. Results. hK2 levels and hK2 x tPSA/fPSA values were significantly elevated in men with PCa. Receiver operating characteristic data revealed that the a rea under the curve for hK2 x tPSA/fPSA was significantly greater than that for tPSA and greater, but not significantly greater, than that for percent fPSA. Also, the cancer-detecting sensitivity was significantly improved (P < 0.05) using hK2 x tPSA/fPSA compared with tPSA and percent fPSA at speci ficity levels of 75% to 90%. At 75% specificity, a sensitivity of 74% was o btained compared with 64% or 54% using percent fPSA or tPSA; at 90% specifi city, the corresponding sensitivity level was 55%, 41%, and 36%, respective ly. Conclusions. Discrimination of men with and without PCa in a randomly selec ted population was improved by measuring hK2 in addition to tPSA and fPSA. UROLOGY 55: 694-699, 2000. (C) 2000, Elsevier Science Inc.