Evaluation of precursor prostate-specific antigen isoform ratios in the detection of prostate cancer.
OBJECTIVE
Disease-associated isoforms of the prostate-specific antigen (PSA) have recently been identified. We evaluated the efficacy of using precursor isoforms of PSA (pPSA) and their ratios for the detection of prostate cancer.


METHODS
Serum concentrations of [-2], [-4], and [-7]pPSA, BPSA, and free PSA (fPSA) were retrospectively measured in 43 selected men. Of the 43 men, 15 had clinical T2 prostate cancer with ultrasound-estimated prostate volumes (PVs) of >50 cm(3), 13 had clinical T2 prostate cancer with (PVs) <25 cm(3), and 15 were prostate cancer-free with PV >50 cm(3). We calculated sum pPSA ([-2]+[-4]+[-7]pPSA). We also compared the ratios of: free/total PSA, [-2]pPSA/fPSA, [-2]pPSA/BPSA, [-2]pPSA/(fPSA-BPSA), [-2]pPSA/(fPSA-sum pPSA), and [-2]pPSA/{fPSA-(sum pPSA+BPSA)} among these three groups.


RESULTS
The median [-2]pPSA/(fPSA-sum pPSA) ratio was significantly higher in men with prostate cancer with or without large PV compared with men with large PV without prostate cancer. Values for median [-2]pPSA/free PSA ratio were higher in men with prostate cancer with or without large PV compared with men with large PV, and without prostate cancer, but the differences were not statistically significant.


CONCLUSIONS
In this preliminary study, [-2]pPSA/(fPSA-sum pPSA) ratio was not associated with prostate gland volume but was associated with prostate cancer. This ratio may be useful in the detection of prostate cancer, particularly in men with larger glands.
Naya
Yoshio
Y
Department of Urology, The University of Texas M.D. Anderson Cancer Center, Houston, 77030, USA.
Fritsche
Herbert A
HA
Bhadkamkar
Viju A
VA
Mikolajczyk
Stephen D
SD
Rittenhouse
Harry G
HG
Babaian
Richard Joseph
RJ
D000230:Adenocarcinoma / Q000097:blood* / Q000175:diagnosis / Q000601:surgery; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D011467:Prostate / Q000473:pathology*; D017430:Prostate-Specific Antigen / Q000097:blood*; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis / Q000601:surgery; D020033:Protein Isoforms / Q000097:blood*; D011498:Protein Precursors / Q000097:blood*; D012372:ROC Curve; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D014408:Biomarkers, Tumor; D020033:Protein Isoforms; D011498:Protein Precursors; D017430:Prostate-Specific Antigen