Prognostic value of urinary prostate cancer antigen 3 (PCA3) during active surveillance of patients with low-risk prostate cancer receiving 5α-reductase inhibitors.

OBJECTIVES: To determine the clinical performance of the urinary prostate cancer antigen 3 (PCA3) test to predict the risk of Gleason grade re-classification amongst men receiving a 5α-reductase inhibitor (5ARI) during active surveillance (AS) for prostate cancer. PATIENTS AND METHODS: Patients with low-risk prostate cancer were enrolled in a prospective Phase II study of AS complemented with prescription of a 5ARI. A repeat biopsy was taken within the first year and annually according to physician and patient preference. In all, 90 patients had urine collected after digital rectal examination of the prostate before the first repeat biopsy. The PCA3 test was performed in a blinded manner at a central laboratory. RESULTS: Using a PCA3-test score threshold of 35, there was a significant difference (P < 0.001) in the risk of being diagnosed with Gleason ≥7 cancer during a median of 7 years of follow-up. Adjusted Cox regression and Kaplan-Meier analyses also showed a significantly higher risk of upgrading to Gleason ≥7 during follow-up for those with a higher PCA3-test score. CONCLUSION: The urinary PCA3 test predicted Gleason grade re-classification amongst patients receiving a 5ARI during AS for low-risk prostate cancer.