title: Spatial distribution of positive cores improves the selection of patients with low-risk prostate cancer as candidates for active surveillance.
abstract: OBJECTIVE
  To test the hypothesis that spatial distribution of positive cores at biopsy is a predictor of unfavourable prostate cancer characteristics at radical prostatectomy (RP) in active surveillance (AS) candidates.
  
  
  METHODS
  We examined the data of 524 patients treated with RP, between 2000 and 2012. All fulfilled at least one of four commonly used AS criteria. Regression models tested the relationship between positive cores spatial distribution, defined as the number of positive zones at biopsy (PBxZ) and tumour laterality at biopsy and two endpoints: (i) unfavourable prostate cancer at RP (Gleason score ≥ 4 + 3, and/or pT3 disease), and (ii) clinically significant prostate cancer (tumour volume ≥ 2.5 mL).
  
  
  RESULTS
  Unfavourable prostate cancer and clinically significant prostate cancer rates were 8 and 25%, respectively. Patients with more than one PBxZ had a 3.2-fold higher risk of harbouring unfavourable prostate cancer, and a 2.3-fold higher risk of harbouring clinically significant prostate cancer compared with their counterparts with one PBxZ (both P = 0.01). Patients with bilateral tumour at biopsy had a 3.3-fold higher risk of harbouring unfavourable prostate cancer and a 1.7-fold higher risk of harbouring clinically significant prostate cancer compared with their counterparts with unilateral tumour at biopsy (both P ≤ 0.04). Some of these results did not reach a statistically significant level, when the analyses were restricted to patients that fulfilled the most stringent AS criteria.
  
  
  CONCLUSIONS
  Positive cores spatial distribution at biopsy should be considered, when advising patients about AS. The addition of this predictor to AS inclusion criteria can help identifying patients at a higher risk of progression, and reduce the rate of inappropriate surveillance of aggressive tumours. However, the most stringent AS criteria (namely John-Hopkins criteria and Prostate Cancer Research International: Active Surveillance criteria) might not benefit from the addition of this predictor. This point warrants further investigation in future studies.
authors.affiliation: Department of Urology, Vita-Salute San Raffaele University, Milan, Italy. firas.abdollah@gmail.com
authors.forename: Firas
authors.initials: F
authors.lastname: Abdollah
authors.forename: Nazareno
authors.initials: N
authors.lastname: Suardi
authors.forename: Umberto
authors.initials: U
authors.lastname: Capitanio
authors.forename: Andrea
authors.initials: A
authors.lastname: Gallina
authors.forename: Maxine
authors.initials: M
authors.lastname: Sun
authors.forename: Luca
authors.initials: L
authors.lastname: Villa
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Scattoni
authors.forename: Marco
authors.initials: M
authors.lastname: Bianchi
authors.forename: Manuela
authors.initials: M
authors.lastname: Tutolo
authors.forename: Nicola
authors.initials: N
authors.lastname: Fossati
authors.forename: Pierre
authors.initials: P
authors.lastname: Karakiewicz
authors.forename: Patrizio
authors.initials: P
authors.lastname: Rigatti
authors.forename: Francesco
authors.initials: F
authors.lastname: Montorsi
authors.forename: Alberto
authors.initials: A
authors.lastname: Briganti
mesh_terms: D006801:Humans; D008297:Male; D008875:Middle Aged; D018579:Patient Selection; D011471:Prostatic Neoplasms / Q000473:pathology* / Q000628:therapy*; D012189:Retrospective Studies; D012307:Risk Factors; D057832:Watchful Waiting
keywords: active surveillance; positive cores; prostate biopsy; prostate cancer; spatial distribution