title: Significance of the Extent of Resection in Modern Neurosurgical Practice of World Health Organization Grade I Meningiomas.
abstract: OBJECTIVE
  Since the prognostic importance of radical resection was introduced in 1957, the neurosurgery practice has undergone several technologic advancements. The aim of this study was to evaluate whether the prognostic value of the extent of resection is still relevant in modern neurosurgical practice.
  
  
  METHODS
  Over a 10-year period, all patients with histologic-confirmed World Health Organization grade I meningiomas and who underwent meningioma surgery were retrospectively analyzed. Survival analyses were performed using Kaplan-Meier analysis and univariate and multivariate Cox proportional-hazards regression analyses.
  
  
  RESULTS
  There were 113 patients included in this study. A better Simpson grade was associated with recurrence-free survival (RFS) 5, 10, and 15 years after surgery (P < 0.001). Comparing Simpson grade I with Simpson grades III and IV, 13.1 and 36.6 times higher hazard ratios were revealed with respect to RFS, respectively. A 7.5 times higher hazard ratio was revealed when comparing Simpson grades II and IV. Additional survival analyses were performed within specific locations and groups with low and high mitotic indices, demonstrating that the extent of resection can add additional information about RFS.
  
  
  CONCLUSIONS
  Simpson grade remains a highly significant predictor of RFS in meningioma-resected patients in modern neurosurgical practice. Extent of resection should therefore be emphasized when predicting prognosis and considering postoperative treatment and frequency of radiologic follow-up after surgery.
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, St. Olavs Hospital, Trondheim, Norway. Electronic address: theolw@stud.ntnu.no.
authors.forename: Theo L
authors.initials: TL
authors.lastname: Winther
authors.affiliation: Department of Laboratory Medicine, Children's and Women's Health, St. Olavs Hospital, Trondheim, Norway; Department of Pathology and Medical Genetics, St. Olavs Hospital, Trondheim, Norway.
authors.forename: Sverre H
authors.initials: SH
authors.lastname: Torp
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008577:Meningeal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D008579:Meningioma / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D008875:Middle Aged; D060787:Neoplasm Grading; D009364:Neoplasm Recurrence, Local / Q000401:mortality* / Q000473:pathology* / Q000517:prevention & control; D019635:Neurosurgical Procedures / Q000379:methods / Q000401:mortality / Q000706:statistics & numerical data; D009664:Norway / Q000453:epidemiology; D015995:Prevalence; D011379:Prognosis; D012307:Risk Factors; D017678:Sex Distribution; D015996:Survival Rate; D016896:Treatment Outcome
keywords: Meningiomas; Recurrence-free survival; Simpson grade; Surgery