Abstract: PD28-07
Sources of Funding: The project described was supported in part by Award Number R01CA158627 from the National Cancer Institute.

Introduction

Gleason Score (GS) upgrading is seen during subsequent biopsy in up to one-third of men in active surveillance (A.S.) programs. Most A.S. biopsies have been performed in a blind fashion. Using MRI/US fusion biopsy, follow-up targeting of MRI lesions can now be performed. We sought to compare such MRI-targeted follow-up biopsies with biopsy of tumor spots outside of MRI-visible lesions. The latter biopsy method, called tracking biopsy, is another feature of MRI/US fusion but has been rarely reported.

Methods

Subjects were 138 consecutive men (mean age 63.4 years) enrolled in A.S. (2009-2016), who had 2 subsequent MRI/US fusion (Artemis) biopsies: confirmatory (6-12 months after initial diagnosis) and surveillance (12 months after that). At confirmatory biopsy, MRI targets and a 12-core template were sampled. At surveillance biopsy, MRI lesions were sampled again and tumor spots detected previously by systematic biopsy were also re-sampled, using the 3D tracking function of the Artemis device (accurate within 3 mm) (Figure). At surveillance biopsy, approximately 5 cores were taken by targeting and 5 by tracking. All men had GS6 lesions at confirmatory biopsy. Upgrading to GS≥3+4 at surveillance biopsy was the endpoint._x000D_

Results

At surveillance biopsy, mean PSA was 4.5 ng/ml (IQR 2.6-5.9) and prostate volume was 46.3 cc (IQR 34.5-59.0). Overall rate of upgrading was 19% (26/138). When MRI-visible lesions were resampled without any tracking biopsies being taken (N=59), upgrading was found in 8 (13%). When prior tumor was sampled by tracking an MRI-invisible lesion (N=23), upgrading was found in 6 (24%). When both targeted and tracking biopsies were performed (N=56), upgrading was found in 12 (21%). Of 56 men having both biopsy methods, upgrading in 12 was detected by targeting in 8 and by tracking in 8; however, 4 of the upgrades (50%) were not detected by each method. Upgrading beyond GS7 was only seen in one patient. _x000D_

Conclusions

At surveillance biopsy for men on A.S., tracking biopsy detects GS upgrading as often as biopsies targeting MRI lesions. However, 50% of upgrading detected by one method were missed by the other. Combining methods increased detection of GS upgrading. Tracking of prior positive sites, even when outside of MRI-visible lesions, is a valuable addition to A.S._x000D_

Funding

The project described was supported in part by Award Number R01CA158627 from the National Cancer Institute.