Outcomes of Serial Multiparametric Magnetic Resonance Imaging and Subsequent Biopsy in Men with Low-risk Prostate Cancer Managed with Active Surveillance

Background: Outcomes of serial multiparametric magnetic resonance imaging (mpMRI) and subsequent biopsy in monitoring prostate cancer (PCa) in men on active surveillance (AS) have not been defined clearly. Objective: To determine whether changes in serial mpMRI can predict pathological upgrade among men with grade group (GG) 1 PCa managed with AS. Design, setting, and participants: Retrospective analysis of men with GG1 on AS with at least two consecutive mpMRI examinations during 2012–2018 who underwent mpMRI/ultrasound fusion or systematic biopsies. Outcome measurements and statistical analysis: Progression on serial mpMRI was evaluated as a predictor of pathological upgrading to GG ≥ 2 on a follow-up biopsy using clinical, pathological, and imaging factors in binary logistic regression. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy were determined. Results and limitations: Of 122 patients, 29 men (23.8%) experienced pathological upgrade on the follow-up biopsy. Progression on mpMRI was not associated with pathological upgrade. The sensitivity, specificity, PPV, and NPV of mpMRI progression for predicting pathological upgrade were 41.3%, 54.8%, 22.2%, and 75%, respectively. Age (odds ratio [OR] 1.17, p = 0.006), Prostate Imaging Reporting and Data System (PI-RADS) score on initial mpMRI (4–5 vs ≤3, OR 7.48, p = 0.01), number of positive systematic cores (OR 1.84, p = 0.03), number of positive targeted cores (OR 0.44, p = 0.04), and maximum percent of targeted core tumor involvement (OR 1.04, p = 0.01) were significantly associated with pathological upgrade. Conclusions: We did not observe an association between mpMRI progression and pathological upgrade; however, a PI-RADS score of 4–5 on initial mpMRI was predictive of subsequent pathological progression. The continued use of systematic and fusion biopsies appears necessary due to risks of reclassification over time. Patient summary: Progression on serial multiparametric magnetic resonance imaging during active surveillance (AS) is not associated with progression on the follow-up biopsy. Both systematic and fusion biopsies are necessary to sufficiently capture progression during AS. No single multiparametric magnetic resonance imaging finding clearly defined clinically significant pathological progression during active surveillance. Continued use of both systematic and fusion biopsy is necessary due to risks of reclassification over time.