title: Perineural invasion in prostate cancer patients who are potential candidates for active surveillance: validation study.
abstract: OBJECTIVE
  To validate whether perineural invasion (PNI) on needle biopsy should represent an exclusion criterion in patients considered for active surveillance (AS). Validation was performed in an independent cohort of patients who fulfilled the Epstein AS criteria, but proceeded to surgery, as recent study showed that PNI in this scenario was not associated with adverse findings on radical prostatectomy.
  
  
  METHODS
  Biopsy, prostatectomy, and clinical data of 845 patients who met the Epstein AS criteria were retrieved from the institutional prostate cancer database. We compared the clinical, biopsy, and prostatectomy findings in patients with and without PNI. All patients had a 10-core biopsy and a radical prostatectomy performed between July 2000 and June 2010.
  
  
  RESULTS
  PNI was present in 63 of 845 (7.4%) patients. Clinical findings were not significantly different between patients with and without PNI. PNI vs no PNI patients demonstrated slightly larger cancer volume on biopsy (2.5% vs 1.8%; P<.001) and greater proportion of 2-core positive biopsies (57.1% vs 36.8%; P=.001). No significant differences were found between the patients with and without PNI regarding the organ-confined disease (95.2% vs 96.4%; P=.5), positive margins (20.6% vs 16.4%; P=.39), tumor volume (8.2% vs 7.3%; P=.36), and prostatectomy Gleason score (≤6 vs >6; P=.13).
  
  
  CONCLUSIONS
  We confirm that finding PNI on biopsy should not influence the decision to exclude patients from AS, if Epstein criteria are met. Although patients with biopsy PNI demonstrated greater volume of cancer and rate of 2-positive cores, PNI on biopsy was not associated with worse prostatectomy findings.
authors: Faculty of Medicine, McGill University, Montreal, Quebec, Canada.
authors: Cvetan
authors: C
authors: Trpkov
authors: Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta, Canada; Calgary Laboratory Services, University of Calgary, Calgary, Alberta, Canada.
authors: Asli
authors: A
authors: Yilmaz
authors: Department of Pathology and Laboratory Medicine, University of Calgary, Calgary, Alberta, Canada; Calgary Laboratory Services, University of Calgary, Calgary, Alberta, Canada. Electronic address: kiril.trpkov@cls.ab.ca.
authors: Kiril
authors: K
authors: Trpkov
mesh_terms: D001706:Biopsy; D006801:Humans; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011467:Prostate / Q000294:innervation* / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000473:pathology*; D012189:Retrospective Studies; D057832:Watchful Waiting