Performance Of Expressed Prostatic Secretion Assays In Prediction Of Surgical Pathology Outcomes In Patients Undergoing Radical Prostatectomy

4645 Background: Prostate cells released into expressed prostatic secretions (EPS) during prostatic massage are easily collected and analyzed. Prior work has shown EPS to perform well as a noninvasive test to predict prostate biopsy outcomes. We evaluate the utility of EPS biomarkers to predict surgical pathology outcomes in patients undergoing radical prostatectomy. Methods: We collected EPS specimens in a blinded prospective study from 138 men undergoing radical prostatectomy for prostate cancer. Specimens were obtained in the operating room under general anesthesia before commencing with radical prostatectomy. Specimens were analyzed for expression of GADH, PC3, Type III and VI TMPRSS2:ERG gene fusions using quantitative PCR. Their characteristic performance for predicting extracapsular extension (ECE) and Gleason sum on surgical pathology specimens was evaluated. These were compared to pre-biopsy PSA, biopsy Gleason sum and digital rectal exam (DRE) findings as predictors of surgical pathology outcomes. Results: The addition of GADH, PCA3, and TMPRSS fusion assays to prostate specific antigen (PSA), DRE, and biopsy gleason sum to predict ECE improved the area under the curve value (AUC) from .810, 95% CI 0.742-0.879; to .838, 95% CI 0.772-0.904. At 80% specificity for ECE, the baseline sensitivity using only DRE, PSA and biopsy Gleason sum was 66%. However, when TMPRSS2:ERG type III, type III+VI or PCA3 were added as predictors, the sensitivity was 71%, 71%, and 75% respectively. Based on these data, this test provides a 95% negative predictive value, compared to 93% for PSA, DRE and biopsy Gleason sum alone. Conclusions: The combination of biopsy Gleason sum and PSA correlate strongly with ECE. The addition of TMPRSS2:ERG and PCA3 markers as predictors improves the sensitivity and negative predictive value in predicting ECE. No significant financial relationships to disclose.