Analysis of pro [-2] PSA: A novel biomarker that significantly improves the detection of prostate cancer

Abstract

Aim: In order to effectively select patients for prostate biopsy more accurate biomarkers of disease are needed. The objective of this study was to analyse the clinical utility of a novel biomarker; pro [-2] PSA in order to inform the decision for prostate biopsy in an Irish cohort of men.

Methods: The serum of 250 men from three tertiary referral centres with pre-biopsy blood draws was analysed for tPSA, fPSA and pro [-2] PSA. From this the phi score was calculated (pro [-2] PSA/fPSA)*√tPSA). Calibration plots, ROC analysis as well as decision curve analysis were utilised to ascertain the potential utility of the phi score.

Results: The phi score was well calibrated in this cohort demonstrating good correlation between predicted probabilities and actual outcome. The AUC for the phi score was 0.72 for the prediction of prostate cancer and 0.78 for the prediction of high grade prostate cancer (gleason ≥ 7), compared to 0.62 and 0.70 for tPSA. Decision curve analysis demonstrated net benefit of the phi score over its entire range of risk probabilities.

Conclusion: The measurement of pro [-2] PSA can increase the accuracy of risk calculation in each individual patient thereby helping to better inform the decision for prostate biopsy in a referral population.