A Low Score in Patients with a Positive PCA3 Urine Test Predicts the Lowest Prognostic Category in the New Grading System for Prostate Carcinoma

Purpose: In this study we evaluate the PCA3 as a tool to improve prostate cancer (PCa) screening and it's capability to predict PCa aggressiveness. Materials and Methods: This retrospective study included data from consecutive patients with suspected PCa who presented to the urology office between November 2009 and April 2016 and were candidates for prostate biopsy. A total of 1038 urine samples were tested in our laboratory with a kit that generated a PCA3 score (s-PCA3). A prostate biopsy was recommended only in those patients with s-PCA3 ≥ 35. Associations between variables were analyzed using the R software. Results: In patients with a positive s-PCA3 (44.5%), a subsequent biopsy was recommended. A total of 151 biopsies were studied, 56.3% yielded a diagnosis of PCa. The probability of a positive biopsy increased as the s-PCA3 increased (p=0.041). The percentage of affected cylinders increased as the s-PCA3 increased (p=0.015). A statistically significant relationship was observed between s-PCA3 and both the Gleason score and the Grade Group (p=0.001 and 0.008, respectively). The best log linear models and a logistic model confirmed the relationships shown previously with Fisher's exact tests. Conclusions: s-PCA3 may serve as an additional marker to reduce the indication for biopsies and avoid overdiagnosis and overtreatment of patients with suspected PCa. The prognostic significance of s-PCA3 was confirmed, as it was associated with tumor volume and Gleason score. Importantly, to our knowledge this is the first time that an association has been demonstrated between s-PCA3 and the new Grade Group.