Comparing magnetic resonance imaging/ultrasound-fusion biopsy and systemic 12-core transrectal ultrasound biopsy for whole gland pathology.

Abstract

84 Background: Historically, pathologic findings from standard 12-core prostate biopsies are upgraded in 25 to 33% of patients after radical prostatectomy (RP). MRI/US fusion prostate biopsy has been shown to upgrade prostate cancer compared to standard 12-core biopsy in 32% of patients. MRI/US fusion biopsy may offer a more accurate representation of whole gland pathology. We evaluate the rate of pathologic upgrade in standard 12-core biopsy and MRI/US fusion biopsy when compared with whole gland pathology from RP. Methods: Patients who underwent random prostate biopsy, fusion biopsy and subsequently RP for prostate cancer from 2012 to 2013 were included. Pathology was reviewed by a single pathologist. The cohort was divided into clinically significant high-grade (Gleason score 4+3 or higher) and clinically insignificant low-grade (Gleason score 3+4 or lower) sub cohorts. Pathological upgrade was defined as any increase in Gleason sum or primary Gleason score. McNemar’s test was used to compare the proportion of patients who were upgraded from random biopsy to RP versus the proportion that were upgraded from fusion biopsy to RP. Results: Sixty eight patients underwent 12-core and fusion prostate biopsy then subsequently RP. Mean prostate-specific antigen was 9.2ng/ml. There are total of 43 patients with clinically insignificant low-grade and 25 patients with clinically significant high-grade. Fusion biopsy upgraded 19 patients (28%) compared to 12-core biopsy, eight of these patients had negative 12-core biopsy. Pathology on the RP specimen upgraded 18 of the 12-core results (26%) compare to only eight fusion biopsy results (11%). (p =0.0095) 14 patients (20%) who had clinically insignificant low-grade disease on 12-core biopsy were upgraded to clinically significant high-grade on RP. Only two patients (3%) with clinically insignificant low-grade from fusion biopsy were upgraded on RP. (p< 0.0005) Conclusions: Prostate cancer detected on MRI/US fusion prostate biopsy has significantly lower rates of pathologic upgrade than standard 12-core biopsy when both were compared to prostatectomy specimens. MRI/US fusion biopsy may represent whole gland pathology more accurately compared to 12-core biopsy.