PHI Is Effective in Identification of Risk in Prostate Cancer Patients

New Orleans—There are two new serum markers associated with the risk and aggressiveness of prostate cancer: the Beckman Coulter Prostate Health Index (PHI) and [2]proPSA (p2PSA). E. David Crawford, MD, and colleagues recently conducted a study designed to determine whether PHI can be used for risk stratification of prostate cancer. The study’s results were reported during a presentation at the AUA 2015 Annual Meeting.

Following initial transrectal biopsies (TRUS) that were negative or detected a low-risk cancer, 72 patients elected template-guided transperineal mapping biopsy (TPMB). Of those, 47 patients had 5-alpha reductase inhibitors to reduce the prostate volume prior to TPMB.

Serum samples drawn prior to TPMB were used to measure prostate specific antigen (PSA), free PSA, and p2PSA. The researchers calculated percent free PSA (%fPSA) = (free PSA/PSA)  100 and PHI= (p2PSA/free PSA)  %[root](PSA).

Clinically significant disease was defined as at least one prostate cancer lesion ≥0.5 cm or Gleason score of 7 or more on TPMB findings. Odds ratio (OR) and statistical significance were determined using Wilcoxon rank sum and logistic regression analysis (LRA). Comparison of performance of PHI was done with receiver operating curve (ROC) analysis.

Among the 72 patients, the mean age was 62.9 years, the mean PSA was 6.7 ng mL-1, the mean free PSA was 17.6%, and the mean PHI was 40.1. Fifty-two patients were diagnosed with cancer, 25 had Gleason scores of 7 or more, and 37 had significantly significant disease.

There was a significant difference in median PHI between patients with malignant versus benign disease (41.8 vs 26.6; P=.0016), as well as between patients with clinically significant disease and insignificant disease (46 vs 31; P=.02). There was also a difference in median PHI in patients with a Gleason score of 7 or more and less than 7 cancer (52.7 vs 39.7; P=.04).

In univariate LRA, PHI identified patients with prostate cancer (OR, 1.11; P=.01) and with clinically significant disease (OR, 1.11; P=.02). For classification of benign versus malignant disease, area under the curve of PHI in ROC analysis was significantly higher than PSA (OR, 0.51; P=.0002) and free PSA (OR, 0.57; P=.033). For classification of clinically significant versus insignificant disease, area under the curve of PHI was significantly higher than PSA (OR, 0.58; P=.042). In a multivariate LRA, both PHI (OR, 1.32; P=.02) and PSA (OR, 4.06; P=.003) predicted patients with clinically significant disease.

The researchers cited the small sample size as the primary limitation to the study.

“Our study demonstrated potential clinical utility of PHI for stratification of patients at high risk for [prostate cancer] and clinically significant disease. Additional studies are required to further validate our findings,” the authors said.

Source: Crawford ED, Arangua P, Jones C, et al. Prostate health index is an effective marker for risk stratification of prostate cancer patients. Abstract of a presentation at the American Urological Association 2015 Annual Meeting, New Orleans, Louisiana, May 18, 2015.