Value of multimodality MRI and MR-guided biopsy at inclusion in an active surveillance protocol for prostate cancer.

105 Background: To prevent overtreatment of insignificant and/or low-risk prostate carcinoma in the PSA screening era, active surveillance is emerging as a treatment strategy for selected patients. In our series we aim to establish whether MRI could aid in correct risk assessment for these patients within the framework of the Prostate Cancer Research International Active Surveillance (PRIAS) study. Methods: We included patients in our protocol based on contemporary criteria for active surveillance: - Diagnosis of prostate cancer by TRUS-guided biopsy. - PSA ≤10 ng/mL, PSA density <0.2 ng/mL/mL - Clinical stage ≤ T2 - Gleason score (GS) ≤3+3=6 - ≤ 2 biopsy cores with cancer All patients underwent multimodality MRI of the prostate, including T2-weighted, diffusion-weighted and dynamic contrast-enhanced MR sequences. When a tumor-suspicious region (TSR) could be identified a targeted MR-guided biopsy (MRGB) was performed to obtain pathology. Patients were referred for definitive treatment in case of GS > 3+3=6 upon MRGB or T3 stage at MRI. Results: In 48 of 49 included patients at least one TSR was identified, with a median of 2 TSRs (range1-4) per patient. MRGB was obtained from every TSR, with a median of 4 MRGBs taken per patient. Five patients had a GS >3+3=6 upon MRGB and were excluded. Three patients were excluded due to suspicion of T3 stage on MRI. Five patient were excluded upon physician’s discretion due to multifocal prostate cancer upon MRGB. Combined multimodality MRI/MRGB in our active surveillance cohort thus excluded 27% (13/49) of patients who were incorrectly stratified as low-risk prostate carcinoma by contemporary criteria. Conclusions: Application of multimodality MRI and MRGB in an active surveillance protocol improves risk stratification, adding onto contemporary PSA and TRUS-guided biopsy criteria for low-risk prostate cancer. This approach might increase safety and reliability of active surveillance for prostate cancer and deserves ongoing prospective evaluation.