Value of 3-T Multiparametric Magnetic Resonance Imaging and Magnetic Resonance–Guided Biopsy for Early Risk Restratification in Active Surveillance of Low-Risk Prostate Cancer

OBJECTIVES: The objective of this study was to evaluate the role of 3-T multiparametric magnetic resonance imaging (MP-MRI) and magnetic resonance-guided biopsy (MRGB) in early risk restratification of patients on active surveillance at 3 and 12 months of follow-up. MATERIALS AND METHODS: Within 4 hospitals participating in a large active surveillance trial, a side study was initiated. Pelvic magnetic resonance imaging, prostate MP-MRI, and MRGB were performed at 3 and 12 months (latter prostate MP-MRI and MRGB only) after prostate cancer diagnosis in 1 of the 4 participating hospitals. Cancer-suspicious regions (CSRs) were defined on prostate MP-MRI using Prostate Imaging Reporting And Data System (PI-RADS) scores.Risk restratification criteria for active surveillance discontinuance were (1) histopathologically proven magnetic resonance imaging suspicion of node/bone metastases and/or (2) a Gleason growth pattern (GGP) 4 and/or 5 and/or cancer multifocality (≥3 foci) in MRGB specimens of a CSR on MP-MRI. RESULTS: From 2009 to 2012, a total of 64 of 82 patients were consecutively and prospectively included and underwent MP-MRI and a subsequent MRGB. At 3 and 12 months of follow-up, 14% (9/64) and 10% (3/30) of the patients were risk-restratified on the basis of MP-MRI and MRGB. An overall CSR PI-RADS score of 1 or 2 had a negative predictive value of 84% (38/45) for detection of any prostate cancer and 100% (45/45) for detection of a GGP 4 or 5 containing cancer upon MRGB, respectively. A CSR PI-RADS score of 4 or higher had a sensitivity of 92% (11/12) for detection of a GGP 4 or 5 containing cancer upon MRGB. CONCLUSIONS: Application of MP-MRI and MRGB in active surveillance may contribute in early identification of patients with GGP 4 or 5 containing cancers at 3 months of follow-up. If, during further follow-up, a PI-RADS score of 1 or 2 continues to have a negative predictive value for GGP 4 or 5 containing cancers, a PI-RADS standardized reported MP-MRI may be a promising tool for the selection of prostate cancer patients suitable for active surveillance.