Performance of MRI-TRUS-guided fusion biopsy to detect progression on active surveillance for low- and intermediate-risk prostate cancer.
43 Background: Active surveillance (AS) is an established treatment option for men with low risk prostate cancer. Its role in intermediate prostate cancer is still being investigated. Recent studies have shown that multiparametric-MRI (mp-MRI) along with MRI-TRUS fusion-guided biopsy may better assess risk in patients eligible for AS, compared to 12-core biopsy, due to improved detection of clinically significant cancers. The objective is to determine the performance of MRI-TRUS guided biopsy for men on AS with both low and intermediate risk disease. Methods: Between 2007-2014 men on AS were included if they had complete mp-MRI and pathology data for 2 or more MRI-TRUS biopsy sessions. Fusion guided biopsy procedures consisted of MRI identified targeted biopsies as well as random 12 core biopsies. Men were allowed to participate in AS with low and intermediate risk prostate cancer, Gleason score ≤ 3+4=7. Progression was defined by patients with initial Gleason 3+3=6 to any Gleason 4, and Gleason 3+4=7 disease progressing to a primary Gleason 4 or higher. Results: 89 men met our study criteria with an average age of 62 years old (range 45-79). 75 men had low risk Gleason 3+3=6 at the outset of AS by 1st biopsy session with a median PSA 5.1 ng/ml. The other 14 men had intermediate risk prostate cancer Gleason 3+4=7 at the outset of AS and a median PSA 4.6 ng/ml. During follow-up, 25 (33%) low risk men progressed to 3+4 or above at a median of 20.6 months. Of these, 19 were found by targeted biopsy. 6 (43%) of the intermediate risk men progressed to Gleason 4+3=7 at a median of 36.8 months. 4 of these progressed on targeted fusion biopsy. In the intermediate risk men, 84 random biopsy cores were require to detect 1 progression versus 15 targeted biopsy cores to detect 1 progression. Conclusions: The majority of patients on AS who progressed were identified by MRI-TRUS targeted biopsy. Less biopsy cores are required to detect progression with targeted biopsy. These results are preliminary and a larger cohort with longer follow-up would be beneficial.