The Role of Multiparametric Magnetic Resonance Imaging/Ultrasound Fusion Biopsy in Active Surveillance

Abstract

Background: Multiparametric magnetic resonance imaging (mpMRI)/ultrasound fusion biopsy (targeted biopsy or TB) may improve detection of high-grade cancers when compared to systematic biopsy (SB).

Objective: To assess TB in active surveillance (AS).

Design, setting, and participants: We retrospectively evaluated SB (12-core sector) and TB among 103 AS men undergoing surveillance biopsy, 54 men undergoing confirmatory biopsy (CB), and 73 men referred for diagnostic biopsy (DB; comparison group). Regions of interest (ROIs) on mpMRI were assigned a PI-RADS score and targeted if the score was ≥3.

Outcome measurements and statistical analysis: Detection of Gleason score (GS) ≥7 by TB and SB was the outcome of interest, except in a multivariable model, for which any cancer was the outcome.

Results and limitations: GS ≥7was detected by either biopsy method in 25 men (24.3%) in the AS group, 12 men (22.2%) in the CB group, and 55 men (75.3%) in the DB group.GS ≥7 was found in 24.3% by SB + TB versus 20.4% by SB in the AS group (p=0.13); in 22.2% by SB + TB versus 16.7% by SB in the CB group (p=0.25); and in 75.3% by SB + TB versus 58.9% by SB in the DB group (p=0.002). The sensitivity for GS ≥7 detection was lower for TB than for SB (p=0.006) in the AS cohort (relative sensitivity ratio 0.33, 95% confidence interval 0.16-0.71). Higher PI-RADS score (4 vs 3, odds ratio [OR] 2.00, p=0.04; 5 vs 3, OR 4.74, p=0.02), lower MRI-estimated prostate volume (OR 1.20 per 10-cm³ lower volume, p=0.01), larger ROI (OR 1.04 per mm, p=0.02), and right-sided ROI (OR 2.27, p=0.01) were associated with finding cancer on TB. A potential limitation is that not all men who presented for biopsy underwent TB and the urologist was not blinded to MRI results before SB.

Conclusions: Owing to the low relative sensitivity of mpMRI for detection of GS ≥7 disease, SB still needs to be performed for men on AS.

Patient summary: This study suggests that image-guided prostate biopsy alone may not be informative for men enrolled in an active surveillance program for prostate cancer.

Keywords: Active surveillance; Multiparametric magnetic resonance imaging; Prostate cancer; Targeted biopsy.