Presentation Authors: Rajiv Jayadevan*, Danielle Barsa, Haoyue Zhang, Lorna Kwan, Steve Zhou, Alan Priester, Jorge Ballon, Leonard Marks, Los Angeles, CA
Introduction: Tracking biopsy is the resampling of previously-documented site(s) of intra-prostatic tumor (CaP). Precise resampling is enabled via electronic storage of specific biopsy sites during MRI-ultrasound fusion biopsy (FB) for future recall. Though tracking can aid in surveillance of specific biopsy sites, it is possible for de novo tumors to develop in other regions of the prostate during active surveillance (AS). We sought to determine the cancer upgrading rate in tracked and non-tracked biopsies, and also to ascertain the frequency of de novo tumor development in a large sample of men undergoing AS.
Methods: Men diagnosed with Gleason Grade Group (GG) 1 CaP between 2009 and 2017 were offered AS. Multiparametric MRI and FB were performed every 12-18 months. All confirmatory biopsies (CB) and follow-up biopsies were performed using a FB system (Artemis). Systematic biopsy was also performed during all biopsy sessions. Sites that were positive for cancer on prior biopsies were resampled via tracking biopsy (Fig 1). Pathologic upgrading was defined as change from GG1 to GG2 or greater. MRIs were reviewed for the development of new regions of interest (ROI).
Results: 168 men had GG1 CaP on both diagnostic and CB, underwent at least 1 follow-up biopsy, and had both tracked and non-tracked biopsies during the same biopsy session (mean age 62.1, prostate specific antigen 4.8 ng/mL, median follow-up time 4.1 years). Of this group, 38% (n=63) were found to have pathologic upgrading to at least GG2 disease. 46% (n=29) of upgrading was detected via tracked biopsy only, 41% (n=26) detected via non-tracked biopsy only, and 13% (n=8) detected via both biopsy types. Of men whose upgrades were detected via only non-tracked biopsy, 35% (n=9) were detected via systematic biopsy, 65% (n=15) via targeted FB, and 8% (n=2) via both. 35% (n=9) of these upgrades appear to be de novo tumors, as upgrading foci were either contralateral to sites of known GG1 tumors (n=3), or found within newly detected ROIs seen on subsequent MRI. Median time from start of AS to development of new ROI containing upgrade was 2.1 years.
Conclusions: Tracking biopsy detects a large percentage of pathologic upgrading for men on AS. Serial MRI and systematic biopsy during AS may detect de novo tumors. Both tracked and non-tracked biopsies are additive in the detection of pathologic upgrading and de novo tumors.
Source of Funding: Supported in part by R01 grants CA158627, CA218547, and CA195505