Magnetic Resonance Imaging at second surveillance biopsy after diagnosis in patients with Grade Group 1 prostate cancer in the Canary Prostate Active Surveillance Study

No clear guidelines exist regarding MRI use after confirmatory biopsy during active surveillance (AS). Our objective was to evaluate MRI performance after confirmatory biopsy in patients with vs. without prior MRI-informed biopsy. Patients in Canary PASS with Gleason grade group (GG) 1 disease undergoing MRI-informed Biopsy 2, defined as second surveillance biopsy after diagnosis, were separated into prior vs. no prior MRI-informed biopsy groups. Primary outcome was reclassification (≥GG2) at MRI-informed Biopsy 2. Reclassification rates and location (systematic cores, targeted cores, both) were compared between groups. Univariable and multivariable logistic regression identified predictors of reclassification. Patients with (n=101) vs. without (n=103) prior MRI-informed biopsy had lower reclassification rates at Biopsy 2 (21% vs. 36%, p=0.017) and lower GG at reclassification (95% vs. 73% of reclassifications to GG2, p=0.039). In multivariable modeling, PI-RADS 4-5 at MRI-informed Biopsy 2 was associated with increased odds of reclassification (OR=2.04 95%CI [1.04-4.05]). The negative predictive value of MRI at Biopsy 2 was 87% (95%CI[78-96]) and 73% (95%CI[61-85]) in with vs. without prior MRI groups, respectively. Reclassification location was identified by targeted cores only in 36% vs. 19% of patients with vs. without prior MRI, respectively (p=0.4). Reclassification location was identified by systematic cores only in 36% vs. 58% of patients with vs. without prior MRI, respectively (p=0.4). These results support MRI use at Biopsy 2 and suggest negative surveillance MRI should not replace Biopsy 2. Both targeted and systematic cores should be taken at Biopsy 2 in patients with and without prior MRI on AS.