title: Initial experience with electronic tracking of specific tumor sites in men undergoing active surveillance of prostate cancer.
abstract: OBJECTIVE
  Targeted biopsy, using magnetic resonance (MR)-ultrasound (US) fusion, may allow tracking of specific cancer sites in the prostate. We aimed to evaluate the initial use of the technique to follow tumor sites in men on active surveillance of prostate cancer.
  
  
  METHODS
  A total of 53 men with prostate cancer (all T1c category) underwent rebiopsy of 74 positive biopsy sites, which were tracked and targeted using the Artemis MR-US fusion device (Eigen, Grass Valley, CA) from March 2010 through January 2013. The initial biopsy included 12 cores from a standard template (mapped by software) and directed biopsies from regions of interest seen on MR imaging (MRI). In the repeat biopsy, samples were taken from sites containing cancer at the initial biopsy. Outcomes of interest at second MR-US biopsy included (a) presence of any cancer and (b) presence of clinically significant cancer.
  
  
  RESULTS
  All cancers on initial biopsy had either Gleason score 3+3 = 6 (n = 63) or 3+4 = 7 (n = 11). At initial biopsy, 23 cancers were within an MRI target, and 51 were found on systematic biopsy. Cancer detection rate on repeat biopsy (29/74, 39%) was independent of Gleason score on initial biopsy (P = not significant) but directly related to initial cancer core length (P<0.02). Repeat sampling of cancerous sites within MRI targets was more likely to show cancer than resampling of tumorous systematic sites (61% vs. 29%, P = 0.005). When initial cancer core length was≥4 mm within an MRI target, more than 80% (5/6) of follow-up tracking biopsies were positive. An increase of Gleason score was uncommon (9/74, 12%).
  
  
  CONCLUSIONS
  Monitoring of specific prostate cancer-containing sites may be achieved in some men using an electronic tracking system. The chances of finding tumor on repeat specific-site sampling was directly related to the length of tumor in the initial biopsy core and presence of tumor within an MRI target; upgrading of Gleason score was uncommon. Further research is required to evaluate the potential utility of site-specific biopsy tracking for patients with prostate cancer on active surveillance.
authors.affiliation: Department of Urology, University of California, Los Angeles, CA; Department of Urology, Stanford University School of Medicine, Stanford, CA.
authors.forename: Geoffrey A
authors.initials: GA
authors.lastname: Sonn
authors.affiliation: Department of Urology, University of California, Los Angeles, CA. Electronic address: cpfilson@gmail.com.
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Filson
authors.affiliation: Department of Urology, University of California, Los Angeles, CA.
authors.forename: Edward
authors.initials: E
authors.lastname: Chang
authors.affiliation: Department of Biomedical Engineering, University of California, Los Angeles, CA; Center for Advanced Surgical and Interventional Technology, University of California, Los Angeles, CA.
authors.forename: Shyam
authors.initials: S
authors.lastname: Natarajan
authors.affiliation: Department of Radiology, University of California, Los Angeles, CA.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Margolis
authors.affiliation: Department of Urology, University of California, Los Angeles, CA.
authors.forename: Malu
authors.initials: M
authors.lastname: Macairan
authors.affiliation: Department of Urology, University of California, Los Angeles, CA.
authors.forename: Patricia
authors.initials: P
authors.lastname: Lieu
authors.affiliation: Department of Pathology, University of California, Los Angeles, CA.
authors.forename: Jiaoti
authors.initials: J
authors.lastname: Huang
authors.affiliation: Biostatistics, University of California, Los Angeles, CA.
authors.forename: Frederick J
authors.initials: FJ
authors.lastname: Dorey
authors.affiliation: Department of Urology, University of California, Los Angeles, CA.
authors.forename: Robert E
authors.initials: RE
authors.lastname: Reiter
authors.affiliation: Department of Urology, University of California, Los Angeles, CA. Electronic address: lmarks@mednet.ucla.edu.
authors.forename: Leonard S
authors.initials: LS
authors.lastname: Marks
mesh_terms: D001706:Biopsy; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D011471:Prostatic Neoplasms / Q000175:diagnosis*; D025321:Surgery, Computer-Assisted / Q000379:methods*; D018084:Ultrasonography, Interventional / Q000379:methods*; D057832:Watchful Waiting
keywords: Active surveillance; Biopsy; Magnetic resonance imaging; Prostatic neoplasms; Ultrasonography