Login to Access Video or Poster Abstract: MP33-05
Sources of Funding: None

Introduction

_x000D_ With over-diagnosis and over-treatment of indolent prostate cancer, non-invasive screening tools that predict low-grade (? Gleason score 6, GS 6) from high-grade (?GS 7) prostate cancer (PCa) will play a significant role in the treatment decision process. Recently, we demonstrated that a urine exosome gene expression assay (ExoDx Prostate (IntelliScore) (EPI)) was able to discriminate high-grade (?GS 7) from low-grade (GS 6) and benign disease biopsy outcomes, thereby improving the identification of men with higher-grade PCa, potentially reducing the number of unnecessary biopsies. In a parallel study, we had also shown that EPI scores were associated with pathologic stage (PS) and radical prostatectomy Gleason score (RP-GS). We now sought to expand these results and further examine outcomes from men enrolled in the biopsy validation trial who had selected surgery. _x000D_

Methods

_x000D_ 430 patients from a previous RP cohort study were re-evaluated using urine EPI scores and ISUP 2014 criteria with respect to RP-GS, PS and cancer volume. Specifically, urine EPI scores from men with biopsy ISUP 1 (i.e. potential candidates for Active Surveillance), were examined along with various clinical variables (including PSA, age, race, family history) for predicting RP upgrading. Additionally, RP outcomes were evaluated from men enrolled in the 519-validation cohort. Preliminary assessment using Spearman and Pearson correlation along with AUC was used to evaluate performance._x000D_

Results

In the 430 RP cohort: 16% ISUP1, 45% ISUP2 (GS3+4),and 37% ? ISUP3 (GS4+3); 85% PSA <10ng/mL and 32% upgrading upon RP. Higher pre-RP urine EPI scores were associated with higher RP-ISUP groups, RP-PS and RP tumor volume (p-value<0.001). In patients from the 519-validation cohort who had a biopsy ISUP1 and chose RP, one third were upgraded and once again higher pre-RP urine EPI scores were significantly associated with a higher RP-ISUP group and higher RP-PS (p-value<0.001). Pre-RP PSA was not able to discriminate RP ISUP upgrading.

Conclusions

The EPI test is a noninvasive, first-catch non-DRE gene expression array that accurately discriminates low-grade from high-grade PCa in ISUP and traditional Gleason score based grading systems. Improved discrimination for predicting higher ISUP groups suggests a potential role in longitudinal monitoring of patients enrolled in Active Surveillance and warrants further validation.

Funding

None