To investigate the relationship between serum [−2]proPSA (p2PSA) and derivatives with chronic histologic prostatic inflammation (CHPI) in men undergoing prostate biopsy for suspected prostate cancer (PCa).

This nested case-control study resulted from an observational prospective trial for the definition of sensibility, specificity, and accuracy of p2PSA, %p2PSA, and Beckman Coulter Prostate Health Index (PHI), in men undergoing prostate biopsy, with a total prostate-specific antigen (PSA) of 4-10 ng/mL and normal digital rectal examination. CHPI was the outcome of interest and defined as the presence of moderate to large infiltration of lymphomononuclear cells with interstitial and/or glandular disruption in absence of PCa. p2PSA, %p2PSA, and PHI were considered the index tests and compared with the established biomarker reference standard tests: tPSA, fPSA, %fPSA.

Of 267 patients subjected to prostate biopsy, 73 (27.3%) patients were diagnosed with CHPI. Comparing CHPI with PCa patients, %p2PSA and PHI were found to be significantly lower, whereas fPSA and %fPSA were significantly higher. %p2PSA and PHI were the most accurate predictors of CHPI at biopsy, significantly outperforming tPSA, fPSA, and %fPSA. On the contrary, no significant differences were found in PSA, p2PSA, and derivatives between CHPI and benign prostatic hyperplasia (BPH) patients.

Our findings showed that p2PSA, %p2PSA, and PHI values might discriminate PCa from CHPI or BPH, but not CHPI from BPH, in men with a total PSA 4-10 ng/mL and normal digital rectal examination. p2PSA isoform and its derivatives could be useful in clinical decision making to avoid unnecessary biopsies in patients with CHPI and elevated tPSA value.