title: Proliferation potential in recurrent acoustic schwannoma following gamma knife radiosurgery versus microsurgery.
abstract: OBJECTIVE
  To evaluate the proliferation potential of recurrent acoustic schwannoma following gamma knife radiosurgery (GKR) versus microsurgery.
  
  
  METHODS
  Retrospective study.
  
  
  METHODS
  A review of surgical records of the House Ear Clinic revealed 8 patients who had undergone GKR and 15 patients who had undergone microsurgery who had unilateral acoustic schwannoma recurrences. Immunohistochemical studies were performed to evaluate the expression of proliferating cell nuclear antigen (PCNA) on archival paraffin-embedded blocks.
  
  
  RESULTS
  All 8 GKR and 15 microsurgical tumors had positive staining for PCNA. The recurrent GKR tumors had significantly lower proliferation levels than in the microsurgical group (P = .03). Two GKR tumors had high proliferation levels.
  
  
  CONCLUSIONS
  Our study indicates that recurrent vestibular schwannomas treated with GKR have lower proliferation potential as assessed by PCNA compared with recurrences following microsurgery. Radiation-induced apoptosis is thought to contribute to the lower tumor cell proliferation in GKR tumor. The two GKR tumors with high proliferation potential could be a result of radiation-induced sporadic mutation, resulting in high tumor cell proliferation.
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, University of California, Irvine Medical Center, Orange, USA.
authors.forename: Frank
authors.initials: F
authors.lastname: Lee
authors.forename: Fred
authors.initials: F
authors.lastname: Linthicum
authors.forename: Gene
authors.initials: G
authors.lastname: Hung
mesh_terms: D017209:Apoptosis / Q000528:radiation effects; D006801:Humans; D008866:Microsurgery; D009364:Neoplasm Recurrence, Local; D009464:Neuroma, Acoustic / Q000473:pathology* / Q000601:surgery*; D018809:Proliferating Cell Nuclear Antigen / Q000032:analysis; D016634:Radiosurgery; D012189:Retrospective Studies
chemical_list: D018809:Proliferating Cell Nuclear Antigen