Complexed prostate-specific antigen and its volume indexes in the detection of prostate cancer

Objectives. To evaluate complexed prostate-specific antigen (cPSA), cPSA de nsity (cPSAD), and cPSA adjusted for the transition zone volume (cPSA-TZ) i n comparison with the free-to-total PSA ratio (F/T PSA) and free-to-complex ed PSA ratio (F/C PSA) as a means of diagnosing prostate cancer. Methods. Transition zone volume was determined in 137 of 142 men who underw ent systematic sextant biopsies and had total PSA (tPSA) values between 4.1 and 10.0 ng/mL, cPSAD and cPSA-TZ were calculated by dividing the cPSA val ue by the whole prostate volume and the transition zone volume, respectivel y. Results. Of the 137 men, 23 (16.8%) had prostate cancer. cPSA predicted the biopsy outcome better than tPSA, F/T PSA, or F/C PSA, although the differe nce was not significant. A cutoff value of 4.1 ng/mL for cPSA provided a sp ecificity of 42% and a sensitivity of 87%. A combination of cPSA and F/C PS A maintained a sensitivity of 83% and gave an increased specificity of 54%. In a subgroup of 65 patients with smaller prostate volumes (less than 45 m L), the diagnostic value of cPSA-TZ was remarkably increased. A cutoff valu e of 0.31 for cPSA-TZ provided a sensitivity of 93% and a high specificity of 72%. Conclusions. cPSA was more specific than tPSA and F/T PSA. As a component o f F/C PSA, free PSA could provide additional value to cPSA, cPSA-TZ and cPS AD could be better indicators for prostate cancer than cPSA. (C) 1999, Else vier Science inc.