Volume-based evaluation of serum assays for new prostate-specific antigen isoforms in the detection of prostate cancer.
OBJECTIVE
Recently, disease-specific isoforms of the prostate-specific antigen (PSA) have been identified. We evaluated the efficacy of precursor isoforms of PSA (pPSA) and an internally cleaved form of PSA referred to as the benign prostatic hyperplasia-associated PSA (BPSA) for the detection of prostate cancer.


METHODS
Serum concentrations of [-2], [-4], and [-7]pPSA, sum pPSA ([-2] + [-4] + [-7]pPSA), and BPSA were retrospectively measured in 43 selected men. The median total PSA levels in men with and without cancer were 6.5 microg/L (range 0.4 to 12.1 microg/L) and 6.1 microg/L (range 3.7 to 21.5 microg/L), respectively. Of the 43 men, 15 had clinical T2 prostate cancer with an ultrasound-estimated prostate volume (PV) of greater than 50 mL, 13 had clinical T2 prostate cancer with PV less than 25 mL, and 15 were prostate cancer free with PV greater than 50 mL.


RESULTS
The median values for BPSA, free-to-total PSA ratio (f/tPSA), and benign-to-total PSA ratio (B/tPSA) differed statistically between men with cancer and a PV less than 25 mL and men with cancer and a PV greater than 50 mL (P <0.05) and between the men with cancer and a PV less than 25 mL and men without cancer and a PV greater than 50 mL (P <0.005). All evaluated variables had no correlation with tumor volume in 15 men who had undergone radical prostatectomy.


CONCLUSIONS
In this preliminary study, the level of [-2], [-4], sum pPSA, and BPSA seemed to be PV related, but only BPSA and B/tPSA and f/tPSA were significantly associated with PV. Therefore, pPSA did not aid in better discriminating cancer from noncancer.
Naya
Yoshio
Y
Department of Urology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030-4009, USA.
Fritsche
Herbert A
HA
Bhadkamkar
Viju A
VA
Mikolajczyk
Stephen D
SD
Rittenhouse
Harry G
HG
Babaian
R Joseph
RJ
D000230:Adenocarcinoma / Q000097:blood* / Q000175:diagnosis / Q000473:pathology / Q000601:surgery; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000097:blood*; D009929:Organ Size; D011467:Prostate / Q000473:pathology*; D017430:Prostate-Specific Antigen / Q000097:blood*; D011468:Prostatectomy; D011471:Prostatic Neoplasms / Q000097:blood* / Q000175:diagnosis / Q000473:pathology / Q000601:surgery; D020033:Protein Isoforms / Q000097:blood*; D011498:Protein Precursors / Q000097:blood*; D012372:ROC Curve; D012189:Retrospective Studies
D014408:Biomarkers, Tumor; D009363:Neoplasm Proteins; D020033:Protein Isoforms; D011498:Protein Precursors; D017430:Prostate-Specific Antigen