Oncology Multiparametric Magnetic Resonance Imaging Enhances Detection of Significant Tumor in Patients on Active Surveillance for Prostate Cancer Hamidreza Abdi, Farshad Pourmalek, Homayoun Zargar, Triona Walshe, Alison C. Harris, Silvia D. Chang, Christopher Eddy, Alan I. So, Martin E. Gleave, Lindsay Machan, S. Larry Goldenberg, and Peter C. Black OBJECTIVE To determine whether multiparametric magnetic resonance imaging (MRI) of the prostate (mpMRI) combined with MRI fusion technology during transrectal ultrasound-guided biopsy can enhance the detection of significant disease in patients with apparent low-risk prostate cancer on active surveillance (AS). MATERIALS AND METHODS We reviewed the charts of 603 patients on AS for localized prostate cancer between January 2006 and September 2013. mpMRI before repeat transrectal ultrasound-guided biopsy was obtained in 111 patients, of whom 69 underwent subsequent fusion biopsy (39 true and 30 cognitive) in addition to standard template biopsy. The results of fusion biopsy were compared with the standard biopsy. The primary endpoint was termination of AS. RESULTS mpMRI detected 118 suspicious lesions in 70 patients (63%). Of these, 42 patients (60%) had lesions with Prostate imaging, reporting, and data system (PIRADS) score 3, and 28 patients (40%) had PIRADS score 4 or 5 lesions. AS was terminated in 27 (24.3%) of the 111 patients who underwent mpMRI. Seventeen patients stopped AS based on mpMRI findings including 16 for pathologic progression in target biopsies and 1 for lesion size increase, whereas the other 10 stopped AS because of pathologic progression in the standard cores (n ¼ 6) or other reasons (n ¼ 4). Use of mpMRI increased the rate of AS termination (27 vs 10; P ¼ .002). On multivariate analysis, PIRADS score 4-5 (vs 3) was the only significant predictor of AS termination (P ¼ .015). CONCLUSION These preliminary retrospective findings suggest that mpMRI with subsequent fusion biopsy en- hances the identification of AS patients requiring definitive treatment. UROLOGY 85: 423e429, 2015. Ó 2015 Elsevier Inc. W idespread prostate-specific antigen (PSA)e based prostate cancer (PCa) screening leads to overdetection and overtreatment of low- risk PCa. The US Preventive Services Task Force has taken the stance that the harms of PSA-based screening outweigh any potential benefits and has recommended against such screening. 1 An alternative approach, how- ever, is to embrace the survival benefit of screening but reduce the harms of overtreatment by adopting active surveillance (AS) more broadly. 2 The Achilles heel of AS is the inherent uncertainty of not being able to pre- dict accurately, which tumors may progress and not knowing if the PCa has been adequately sampled with a standard systematic transrectal ultrasound (TRUS)e guided biopsy. PCa remains the only cancer that is diagnosed by blind biopsy without tumor visualization. Multiparametric MRI of the prostate (mpMRI) offers the potential opportunity to overcome these limitations by imaging and enabling targeted biopsy of these lesions. 3-8 More complete and more precise sampling of the prostate should reduce the uncertainty of AS and facilitate its wider acceptance, by both patients and physicians, as a treatment option. We hypothesized that mpMRI with MRI-TRUS fusion biopsy would identify significant cancers more frequently in AS patients, thereby enriching the AS patient population for truly low-risk disease and identifying those patients who should undergo definitive therapy. Here, we report on the utility of mpMRI in pa- tients on AS. Financial Disclosure: The authors declare that they have no relevant financial interests. From the Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada; and the Department of Radiology, University of British Columbia, Vancouver, British Columbia, Canada Address correspondence to: Peter C. Black, M.D., F.A.C.S., F.R.C.S.C., Department of Urologic Sciences, Vancouver Prostate Centre, University of British Columbia, Level 6, 2775 Laurel Street, Vancouver, BC, Canada V5Z 1M9. E-mail: pblack@mail.ubc.ca Submitted: July 15, 2014, accepted (with revisions): September 25, 2014 ª 2015 Elsevier Inc. All Rights Reserved http://dx.doi.org/10.1016/j.urology.2014.09.060 0090-4295/15 423