Measurement of free PSA in the diagnosis and staging of prostate cancer.
The purpose of this study was to analyze the role of total prostate-specific-antigen (PSA) and free-PSA levels in the diagnosis and clinical staging of prostate cancer. We determined total-PSA serum concentration and free-PSA percentage in 352 patients, 234 with benign prostatic hyperplasia (BPH) and 118 with prostate cancer. Clinical stage of patients with prostate cancer was T1 N0 M0 in 17, T2 N0 M0 in 27, T3-4 N0 M0 in 34 and T1-4 N0-3 M0-1 in 40. Median total-PSA serum concentration was 3.1 ng/ml in patients with BPH and 26.9 ng/ml in patients with prostate cancer, p < 0.0001. Median free-PSA level was 16.7% in patients with BPH and 8.1% in patients with prostate cancer, p < 0.0001. A cutpoint of 4.0 ng/ml detected 96.6% of the prostate cancer, but the percent rate of negative biopsies was 42.1%. For a free-PSA level of 25% in patients with total PSA greater than 4.0 ng/ml, the sensitivity was 97.4%, and the decrease in negative biopsies was 21%. Median total-PSA serum concentration in patients with prostate cancer according to clinical stage was 8.9 ng/ml for T1 N0 M0, 12.9 ng/ml for T2 N0 M0, 29.9 ng/ml for T3-4 N0 M0 and 317 ng/ml for T1-4 N1-3 M0-1, p < 0.001. Median free-PSA levels were 10.1%, 8.1%, 8.4% and 6.1% respectively, p > 0.05. According to the Gleason score, median total-PSA serum concentration was 10.6 ng/ml in patients between 2 and 4, 22.3 ng/ml between 5 and 7 and 77.0 ng/ml between 8 and 10, p < 0.05. Free PSA levels were 7.7%, 8.7% and 6.6% respectively, p > 0.05. Determination of percentage of free PSA appears to be a helpful method for enhancing the specificity of total PSA. A cutpoint of 25% could detect more than 95% of prostate cancers and avoid 21% of negative biopsies in patients with total PSA above 4.0 ng/ml. However, this parameter does not provide additional information about the clinical staging of prostate cancer.
Morote
J
J
Department of Urology Vall d'Hebron University Hospital, Autonomous University of Barcelona, Spain.
Raventós
C X
CX
Lorente
J A
JA
Lopez-Pacios
M A
MA
Encabo
G
G
de Torres
I
I
Andreu
J
J
D001706:Biopsy; D001798:Blood Proteins / Q000378:metabolism; D006801:Humans; D008297:Male; D009367:Neoplasm Staging; D017430:Prostate-Specific Antigen / Q000097:blood*; D011470:Prostatic Hyperplasia / Q000097:blood; D011471:Prostatic Neoplasms / Q000097:blood / Q000175:diagnosis* / Q000473:pathology*; D011485:Protein Binding
D001798:Blood Proteins; D017430:Prostate-Specific Antigen