SelectMDx versus Prostate Health Index in the identification of high-grade prostate cancer.

Abstract

30 Background: A major clinical challenge is to identify patients at increased risk of high-grade prostate cancer (PCa) (Gleason scores ≥ 7) before biopsy. Thus, we evaluated the clinical utility of SelectMDx and Prostate Health Index (phi) tests for diagnosis of high-grade PCa as compared with transperineal mapping biopsy (TMB) results, where an average of 80 prostate needle biopsies are taken every 5 mm for a diagnostic accuracy of 98%. Methods: 70 patients were selected who had TMB. They were evaluated with both SelectMDx and phi tests from before or after TMB; all had serum and post-digital rectal examination urine samples collected prior to treatment, stored in our biorepository. phi was evaluated using proPSA, free PSA and total PSA in serum. SelectMDx test measured mRNA levels of the HOXC6 and DLX1 in post-DRE urine. Published data shows that phi <27 and SelectMDx score = 0% correlate with patients free of HG PCa. Test results were compared against TMB histopathology data. Multivariate logistic regression (MLS) analyses and receiver operating characteristic (ROC) curves were used to determine diagnostic accuracy. DeLong test was used to determine statistical significance of ROC curves. All analyses were done for diagnosis of any PCa and high-grade PCa. Results: TMB histopathology showed 17/70 patients with no PCa and 22/53 with high-grade PCa. The sensitivity, specificity, positive (PPV) and negative (NPV) predictive values of each test are shown in the table below. Pairwise ROC comparison showed no statistically significant difference in the area under the curve of diagnosing PCa (0.75 vs 0.65) and high-grade PCa (0.71 vs 0.81) by phi and SelectMDx tests respectively. MLS analyses showed phi was significantly better than SelectMDx for diagnosing PCa (β = 0.054; p=0.005) and SelectMDx was significantly better than phi for diagnosing high-grade PCa (β = 8.45; p=0.0002). Conclusions: With high sensitivity and NPV, SelectMDx test is more useful than phi for screening patients at risk of high-grade PCa prior to biopsy. [Table: see text]