Clinical performance of PCA3 and TMPRSS2:ERG urinary biomarkers for African American men undergoing prostate biopsy.

Abstract

91 Background: Urinary assaysfor PCA3 and TMPRSS2:ERG (T2:ERG) fusion are established biomarkers for the detection of prostate cancer (PCa). However few African Americans (AA) have been included in previous studies. We sought to determine the performance characteristics of these assays in a racially diverse group of men who elected to undergo prostate biopsy. Methods: Following IRB approval, from 12/2013-10/2014, post digital rectal exam urine was collected in 152 patients without a diagnosis of PCa, prior to biopsy. PCA3 and T2:ERG RNA copies were quantified using transcription-mediated amplification assays and normalized to PSA mRNA copies. Results: Of the 152 patients who met study inclusion, 93 (61%) were AA, 59 were non-AA (39%); 72(47%) were diagnosed with PCa (55% AA, 36% non-AA). Both PCA3 and T2:ERG scores were greater in men with biopsy-proven PCa, those with ≥3 PCa cores, ≥33.3% PCa cores, >50% PCa involvement of greatest biopsy core and Epstein significant PCa (all p-values ≤ 0.02). PCA3 but not T2:ERG scores were greater in men with Gleason grade ≥7 (p = 0.0003). ROC analyses for prediction of biopsy outcome resulted in AUCs of 0.7, 0.61 and 0.59 for PCA3, T2:ERG and serum PSA. For the subgroup of AA, PCA3 and T2:ERG scores were greater in men with biopsy-proven PCa, those with ≥3 PCa cores, ≥33.3% PCa cores, >50% PCa involvement of greatest biopsy core and Epstein significant PCa (all p-values ≤0.01). Both PCA3 and T2:ERG scores were greater in men with Gleason grade ≥7 (p ≤ 0.03). ROC analyses for prediction of biopsy outcome for AA only resulted in AUCs of 0.66, 0.66 and 0.58 for PCA3, T2:ERG and serum PSA. For the non-AA cohort, PCA3 scores were greater in men with biopsy-proven PCa, those with ≥3 PCa cores, ≥33.3% PCa cores, >50% PCa involvement of greatest biopsy core, Epstein significant PCa and Gleason grade ≥7 (all p-values ≤ 0.03). T2:ERG did not reach significance for any of these variables. In this subgroup, ROC analyses for prediction of biopsy outcome resulted in AUCs of 0.73, 0.54 and 0.56 for PCA3, T2:ERG and serum PSA. Conclusions: In AA men undergoing prostate biopsy, both PCA3 and T2:ERG urinary assays demonstrate clinical utility in predicting biopsy outcome and PCa disease characteristics.