PD55-06\u2003COMPARISON OF MRI/FUSION VERSUS TRUS CONFIRMATORY BIOPSY IN ACTIVE SURVEILLANCE PATIENTS

Abstract

INTRODUCTION AND OBJECTIVES: Selection of appropriate patients for active surveillance (AS) is a key safety issue for conservative management of low-risk localized prostate cancer. Confirmatory biopsy is often performed within a year of diagnosis in order to identify occult high-grade or high-volume cancer, and magnetic resonance imaging (MRI) has been increasingly used to guide confirmatory biopsies. Its overall utility versus conventional transrectal ultrasound (TRUS) biopsy, however, remains unknown. Therefore, we sought to determine the degree to which each technique identified pathologic features that rendered patients ineligible for AS on confirmatory biopsy. METHODS: Cohort consisted of 645 men who chose AS and underwent confirmatory biopsy between 2010 and 2018 with either a repeat TRUS biopsy (575 men) or MRI fusion biopsy (70 men) (which included 12 standard cores in addition to targeted cores). Our primary outcome of interest was AS ineligibility on confirmatory biopsy as defined using the previously published eligibility definitions from 4 major AS cohorts (John Hopkins University [JHU], University of Toronto, Canary Prostate Active Surveillance Study [PASS], and University of California San Francisco [UCSF]). RESULTS: Patients who underwent MRI had a higher average number of cores taken (16.62 versus 14.48, p=0.0001) and larger maximum percent core involvement (22.19% versus 15.34%, p=0.015). In the TRUS protocol, 8-17% of men were no longer eligible for AS after a confirmatory biopsy, whereas, in the MRI protocol, 10-32% were ineligible (Table). JHU AS criteria are the most strict, and in our cohort resulted in the highest rate of ineligibility for AS. Amongst the 4 AS cohorts, MRI confirmatory biopsy was significantly more likely to rule a patient ineligible for AS according to the JHU eligibility criteria (32% versus 17%, respectively, p=0.040), with no significant difference in the other cohorts. CONCLUSIONS: When adhering to strict inclusion criteria for AS, use of MRI-TRUS fusion for confirmatory biopsy results in an increased rate of ineligibility. When applying more inclusive criteria, MRI use increases the number of cores taken and maximum percent tumor involvement per core, without altering eligibility. Thus, MRI-TRUS fusion biopsy may have utility if the intent is to remain on AS only if still meeting JHU criteria after confirmatory biopsy. Table. No title available. Source of Funding: None