Does [-2]Pro-Prostate Specific Antigen Meet the Criteria to Justify Its Inclusion in the Clinical Decision-Making Process?

INTRODUCTION: To assess whether [-2]pro-prostate-specific antigen (p2PSA) meets the criteria to justify its inclusion in a predictive model of prostate cancer (PCa) diagnosis and in the clinical decision-making process.

MATERIALS AND METHODS: A total 172 men with total prostate-specific antigen of 2-10 ng/mL underwent measurement of free PSA and p2PSA before prostate biopsy in an observational and prospective study. From these measurements, the Prostate Health Index (PHI) was calculated. Clinical and analytical predictive models were created incorporating PHI.

RESULTS: Of 172 men, 72 (42%) were diagnosed with PCa, 33 (46%) of whom were found to be with high-grade disease. PHI score was the most predictive of biopsy outcomes in terms of discriminative ability (area under the curve = 0.79), with an added gain in predictive accuracy of 17%. All the models that incorporated PHI worked better in terms of calibration close to 45° on the slope. In the decision curve analysis, at a threshold probability of 40% we could prevent 82 biopsies, missing only 16 tumors and 5 high-grade tumors.

CONCLUSIONS: PHI score is a more discriminant biomarker, has superior calibration and superior net benefit, and provides a higher rate of avoided biopsies; thus, it can be useful for aiding in making a more informed decision for each patient.