V6-06: Use of MRI/US fusion for targeted prostate biopsy in Active Surveillance

V6-06: Use of MRI/US fusion for targeted prostate biopsy in Active Surveillance


Introductions and Objectives
Active surveillance (AS) is an excellent management strategy for men with low-risk prostate cancer (CaP). However, risk assessment has historically been made by blind biopsy, and later re-classification is common. We demonstrate the use and potential value of multi-parametric MRI (mp-MRI) and targeted fusion biopsy for men in AS.

Men referred for low-risk CaP were enrolled in IRB-approved AS at UCLA from 3/10-1/13, and within 6 months underwent confirmatory biopsy (Bx 1) using MRI/ultrasound fusion with the Artemis device (Eigen, Grass Valley, CA). MRI targets were graded 1-5 per increasing level of CaP suspicion. Directed biopsies were taken from MRI targets and from systematic sites with method previously described (J Urol 189: 86, 2012). At a follow-up fusion biopsy (Bx 2), performed 12 months after Bx 1, all prior positive sites were re-sampled using electronic tracking.

At Bx 1, 74 CaP sites were found in 53 men, 85% of whom had Gleason sum (GS) 6. At Bx 2, 29/74 sites (39%) were found to contain CaP; when CaP was found initially within an MRI target, that rate increased to 14/23 (61%) (Fig 1). The presence of CaP at Bx 2 was also related to cancer core length (CCL, mm) at Bx 1. When CaP sites were within an MRI target and the initial CCL ≥4mm, 5/6 (83%) had CaP in that target on Bx 2. 9/74 CaP sites (9/53 men, 17%) were upgraded to GS ≥7; only 3/53 men (6%) were upgraded to primary Gleason ≥4 (Fig 2). Significant CaP (GS ≥7 or CCL ≥4mm) was found in 3/51 systematic sites (6%), in 4/11 intermediate-grade targets (36%), and in 7/10 high-grade targets (70%).

Among men followed in AS with MRI/US fusion biopsy, cancer was twice as likely to be present in targeted than in systematic samples. MRI grade of target and CCL at initial fusion biopsy were directly related to CaP detection rate at follow-up fusion biopsy. MRI grading was correlated with significant CaP on repeat biopsy. At follow-up fusion biopsy, upgrading was seen in only (9/53 men, 17%), indicating improved accuracy of initial biopsy. Fusion biopsy may allow better patient selection for AS than conventional biopsy.

Funding: Supported by Award Number R01CA158627 from the National Cancer Institute, UCLA Clinical and Translational Sciences Institute (Grant Number UL1TR000124), the Beckman Coulter Foundation, the Jean Perkins Foundation, and the Steven C. Gordon Family Foundation.