PROSPECTIVE EVALUATION OF PERCENT FREE-PSA AND COMPLEXED-PSA FOR EARLY DETECTION OF PROSTATE-CANCER

Aims of the study: Retrospective studies investigating the use of perc ent free-PSA for early detection of prostate cancer were limited for v arious reasons: by their use of long-term stored sera, poor mix of non -cancer to cancer cases and the use of only men with PSA values betwee n 4.0 and 10.0 ng/mL. This prospective study investigates the clinical utility of percent free-PSA and complexed-PSA for early detection of prostate cancer in 219 consecutive men presenting for prostate biopsy Methods: Of 246 consecutive men who underwent ultrasound guided sextan t biopsy of the prostate for PSA elevation and/or suspicious digital r ectal exam, 219 men had serum total PSA levels between 2.0 and 20.0 ng /mL and were included in this study. Serum total, free and complexed ( PSA-ACT) were measured (Hybritech Inc.). Results: Pathologic examinati ons demonstrated that 72% and 28% of the biopsies were non-cancer and cancer respectively. The mean percent free-PSA was statistically diffe rent between the groups (cancer 14% +/- 6.4 and non-cancer 18 +/- 9%, P < 0.001) and improved cancer detection. PSA-ACT provided only modest improvement in cancer detection over that of total PSA. Among this co hort of men, the optimal total PSA reflex range for percent free-PSA w as 3.0 - 7.0 ng/mL (38% specificity) with a percent free-PSA cut-off o f 20% (95% sensitivity) yet only affected 56% of the cases. Conclusion s: PSA-ACT added very little additional value to the clinical utility of total PSA for early detection. Percent free-PSA performed well for all reflex ranges. A sensitivity and specificity of 95% and 20% respec tively were obtained using a single cut-off of 25% for percent free-PS A for the group of men with total PSA values between 4.0 and 10.0 and correlated well with recently reported prospective analyses.