Preoperative prostate-specific antigen isoform p2PSA and its derivatives, %p2PSA and prostate health index, predict pathologic outcomes in patients undergoing radical prostatectomy for prostate cancer

Abstract

Background: Currently available predictive models fail to assist clinical decision making in prostate cancer (PCa) patients who are possible candidates for radical prostatectomy (RP). New biomarkers would be welcome.

Objective: Test the hypothesis that prostate-specific antigen (PSA) isoform p2PSA and its derivates, percentage of p2PSA to free PSA (%p2PSA) and the Prostate Health Index (PHI), predict PCa characteristics at final pathology after RP.

Design, setting, and participants: An observational prospective study was performed in 350 consecutive men diagnosed with clinically localised PCa who underwent RP.

Measurements: We determined the predictive accuracy of serum total PSA (tPSA), free PSA (fPSA), fPSA-to-tPSA ratio (%fPSA), p2PSA, %p2PSA, and PHI. The primary end point was to determine the accuracy of these biomarkers in predicting the presence of pT3 disease, pathologic Gleason sum≥7, Gleason sum upgrading, and tumour volume<0.5 ml.

Intervention: Open retropubic and robot-assisted laparoscopic RP was performed. Pelvic lymphadenectomy was performed according to baseline oncologic parameters and the surgeon's judgement.

Results and limitations: The %p2PSA and PHI levels were significantly higher in patients with pT3 disease, pathologic Gleason sum≥7, and Gleason sum upgrading (all p values<0.001). Conversely, %p2PSA and PHI levels were significantly lower in patients with tumour volume<0.5 ml (p<0.001). By univariate analysis, both %p2PSA and PHI were accurate predictors of pT3 disease, pathologic Gleason sum≥7, Gleason sum upgrading, and tumour volume<0.5 ml. By multivariate analyses, the inclusion of both %p2PSA and PHI significantly increased the predictive accuracy of a base multivariate model (excluding the tumour volume prediction for both variables, and Gleason sum upgrading for the model including %p2PSA) that included patient age, tPSA, fPSA, f/tPSA, clinical stage, and biopsy Gleason sum.

Conclusions: We found that p2PSA and its derivatives are predictors of PCa characteristics at final pathology after RP and are more accurate than currently available markers.