title: Identifying the index lesion with template prostate mapping biopsies.
abstract: OBJECTIVE
  The natural history of prostate cancer might be driven by the index lesion. We determined the percent of men in whom the index lesion could be defined using transperineal template prostate mapping biopsies.
  
  
  METHODS
  Included in study were consecutive men undergoing transperineal template prostate mapping biopsies with biopsies grouped into 20 zones. Men with clinically significant disease in only 1 prostate area were considered to have an identifiable index lesion. We evaluated the impact of using 2 definitions of clinically significant disease (Gleason grade pattern 4 and/or lesion volume 0.5 cc or greater) and 2 clustering rules (stringent and tolerant) to define the index lesion.
  
  
  RESULTS
  Included in study were 391 men with a median age of 62 years (IQR 58-67) and a median prostate specific antigen of 6.9 ng/ml (IQR 4.8-10.0). Of the men 269 (69%) were previously diagnosed with prostate cancer. By deploying a median of 1.2 cores per ml (IQR 0.9-1.7) cancer was diagnosed in 82.9% of the men (324 of 391) with a median of 6 positive cores (IQR 2-9), a median maximum cancer core length of 5 mm (IQR 3-8) and a total cancer core length per zone of 7 mm (IQR 3-13). Insignificant disease was found in 26.3% to 42.9% of cases. When a stringent spatial relationship was used to define individual lesions, 44.4% to 54.6% of patients had 1 index lesion and 12.7% to 19.1% had more than 1 area with clinically significant disease. These proportions changed to 46.6% to 59.2% and 10.5% to 14.5%, respectively, when less stringent spatial clustering was applied.
  
  
  CONCLUSIONS
  Transperineal template prostate mapping biopsies enable the index lesion to be localized in most men with clinically significant disease. This information may be important to select appropriate candidates for targeted therapy and to plan a tailored treatment strategy in men undergoing radical therapy.
authors.affiliation: Division of Surgery and Interventional Science, University College London, London, United Kingdom; Department of Urology, University College Hospitals National Health Service Foundation Trust, London, United Kingdom; Department of Urology, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland. Electronic address: massimo.valerio.12@ul.ac.uk.
authors.forename: Massimo
authors.initials: M
authors.lastname: Valerio
authors.affiliation: Division of Surgery and Interventional Science, University College London, London, United Kingdom; Department of Urology, University College Hospitals National Health Service Foundation Trust, London, United Kingdom.
authors.forename: Chukwuemeka
authors.initials: C
authors.lastname: Anele
authors.affiliation: Department of Histopathology, University College Hospitals National Health Service Foundation Trust, London, United Kingdom.
authors.forename: Alex
authors.initials: A
authors.lastname: Freeman
authors.affiliation: Department of Histopathology, University College Hospitals National Health Service Foundation Trust, London, United Kingdom.
authors.forename: Charles
authors.initials: C
authors.lastname: Jameson
authors.affiliation: Department of Urology, Royal Free Hospital National Health Service Trust, London, United Kingdom.
authors.forename: Paras B
authors.initials: PB
authors.lastname: Singh
authors.affiliation: Centre for Medical Imaging Computing, University College London, London, United Kingdom.
authors.forename: Yipeng
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Division of Surgery and Interventional Science, University College London, London, United Kingdom; Department of Urology, University College Hospitals National Health Service Foundation Trust, London, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Emberton
authors.affiliation: Division of Surgery and Interventional Science, University College London, London, United Kingdom; Department of Urology, University College Hospitals National Health Service Foundation Trust, London, United Kingdom.
authors.forename: Hashim U
authors.initials: HU
authors.lastname: Ahmed
mesh_terms: D000368:Aged; D001706:Biopsy / Q000379:methods; D006801:Humans; D008297:Male; D008875:Middle Aged; D011467:Prostate / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000473:pathology*; D013520:Urologic Surgical Procedures
keywords: biopsy; diagnosis; prostate; prostatectomy; prostatic neoplasms