Risk Stratification by Urinary PCA3 Testing Prior to MRI-US Fusion-Targeted Prostate Biopsy among Men with No Previous History of Biopsy

Abstract Objectives To determine whether a combination of PCA3 and MRI suspicion score (mSS) could further optimize detection of prostate cancer on MRF-TB among men with no previous history of biopsy. Materials and Methods 187 men presenting to our institution between 6/12 and 8/14 who underwent multiparametric MRI and PCA3 prior to MRF-TB. Biopsy results, stratified by biopsy indication and PCA3 score, were recorded. Receiver operating characteristics (ROC) curves and multivariable logistic regressions were utilized to model the association of PCA3 and mSS with cancer detection on MRF-TB. Results PCA3 is associated with cancer detection on MRF-TB for men with no prior biopsies (AUC = 0.67, 95% CI 0.59-0.76). Using a cutoff of ≥35, PCA3 was associated with cancer risk among men with mSS 2-3 (p=0.004), but not among those with mSS 4-5 (p=0.340). The interaction of PCA3 and mSS demonstrated significantly higher discrimination for cancer than mSS alone (AUC: 0.83 vs. 0.79, p=0.0434). Conclusions Urinary PCA3 is associated with mSS and the detection of cancer on MRF-TB for men with no prior biopsies. PCA3 notably demonstrates a high negative predictive value among mSS 2-3. However, in the case of high suspicion mpMRI, PCA3 is not associated with cancer detection on MRF-TB adding little to cancer diagnosis. Further studies are needed to evaluate the utility of PCA3 in predicting cancer among men with normal mpMRI.