Active Surveillance Magnetic Resonance Imaging Study (ASIST): Results of a Randomized Multicenter Prospective Trial

Background and objective: This study aimed to determine, in men recently diagnosed with grade group 1 (GG1) prostate cancer, if magnetic resonance imaging (MRI) with targeted biopsy could identify a greater proportion of men with GG >= 2 cancer on their confirmatory biopsy compared with systematic biopsies. The study was registered with www.clinicaltrials.gov (NCT01354171). Design, setting, and participants: This study is a prospective, randomized, multicenter, open-label trial. Eligible patients were men diagnosed with GG1 cancer within 1 yr prior to study entry in whom a confirmatory biopsy was indicated. Patients were randomized to 12-core systematic biopsy or MRI with systematic and targeted biopsy using the Artemis fusion targeting system. The primary end point was the proportion upgraded to GG >= 2 in each arm. Results and limitations: In total, 296 men were registered and 273 randomized. Of the MRI group, 64% had a region of interest. No difference was observed in the rate of GG >= 2 upgrading (the intent-to-treat population, p = 0.7, and per-protocol [PP] population, p = 0.4), GG >= 2 upgrading within each stratum separately, or GG >= 3. After central pathology review, upgrading was observed in 36/132 (27%) men in the systematic biopsy arm and 42/127 (33%) men in the MRI arm (p = 0.3). Upgrading was seen in 19/137 (14%) patients in the MRI arm on targeted biopsy alone (median, 2 cores) compared with 31/136 (23%) in the systematic biopsy arm (median, 12 cores; p = 0.09). In the MRI arm, 8/127 (6.5%) patients had GG >= 2 disease identified on targeted biopsy, but <= GG1 on the systematic biopsy, and 10/127 (7.9%) patients had GG >= 2 disease identified by systematic biopsy but <= GG1 on targeted biopsy. Significant differences in upgrading on targeted biopsies were seen between sites, likely reflecting different levels of expertise with the targeted biopsy technique. Conclusions: The addition of MRI with targeted biopsies to systematic biopsies did not significantly increase the upgrading rate compared with systematic biopsy alone. Furthermore, 2-core targeted biopsies alone resulted in a nonsignificant trend to less upgrading than 12-core systematic biopsy (p = 0.09). In men on active surveillance, targeted biopsies identify most, but not all, clinically significant cancers. (C) 2018 European Association of Urology. Published by Elsevier B.V. All rights reserved.