title: Significance of Simpson grading system in modern meningioma surgery: integration of the grade with MIB-1 labeling index as a key to predict the recurrence of WHO Grade I meningiomas.
abstract: OBJECTIVE
  Techniques for the surgical treatment of meningioma have undergone many improvements since Simpson established the neurosurgical dogma for meningioma surgery in his seminal paper published in 1957. This study aims to assess the clinical significance and limitations of the Simpson grading system in relation to modern surgery for WHO Grade I benign meningiomas and to explore the potential of the cell proliferation index to complement the limitations in predicting their recurrence.
  
  
  METHODS
  The surgical records of patients who underwent resection of intracranial meningiomas at the University of Tokyo Hospital between January 1995 and August 2010 were retrospectively analyzed. The authors investigated the relationships between recurrence-free survival (RFS) and Simpson grade or MIB-1 labeling index value.
  
  
  RESULTS
  A total of 240 patients harboring 248 benign meningiomas were included in this study. Simpson Grade IV resection was associated with a significantly shorter RFS than Simpson Grade I, II, or III resection (p<0.001), while no statistically significant difference was noted in RFS between Simpson Grades I, II, and III. Among meningiomas treated by Simpson Grade II and III resections, however, multivariate analysis revealed that an MIB-1 index of 3% or higher was associated with a significantly shorter time to recurrence.
  
  
  CONCLUSIONS
  The clinical significance of the different management strategies related to Simpson Grade I-III resection may have been diluted in the modern surgical era. The MIB-1 index can differentiate tumors with a high risk of recurrence, which could be beneficial for planning tailored optimal follow-up strategies. The results of this study appear to provide a significant backing for the recent shift in meningioma surgery from attempting aggressive resection to valuing the quality of the patient's life.
authors.affiliation: Department of Neurosurgery, University of Tokyo, Tokyo, Japan. sooya-tky@umin.ac.jp
authors.forename: Soichi
authors.initials: S
authors.lastname: Oya
authors.forename: Kensuke
authors.initials: K
authors.lastname: Kawai
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Nakatomi
authors.forename: Nobuhito
authors.initials: N
authors.lastname: Saito
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D003627:Data Interpretation, Statistical; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D019394:Ki-67 Antigen / Q000032:analysis*; D008279:Magnetic Resonance Imaging; D008297:Male; D008579:Meningioma / Q000473:pathology* / Q000601:surgery*; D008875:Middle Aged; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology / Q000473:pathology; D019635:Neurosurgical Procedures; D012008:Recurrence; D012189:Retrospective Studies; D018570:Risk Assessment; D016019:Survival Analysis; D016896:Treatment Outcome; D014944:World Health Organization; D055815:Young Adult
chemical_list: D019394:Ki-67 Antigen