title: Clinicopathological factors related to regrowth of vestibular schwannoma after incomplete resection.
abstract: OBJECTIVE
  The authors retrospectively analyzed various clinicopathological factors to determine which are related to regrowth during a long-term follow-up period in patients who underwent incomplete vestibular schwannoma (VS) resection.
  
  
  METHODS
  This study involved 74 patients (25 men and 49 women) in whom a VS was treated surgically via the lateral suboccipital approach, and who had postoperative follow-up periods exceeding 5 years. The mean follow-up was 104.1 months (range 60-241 months), and the mean patient age at surgery was 48.1 years (range 19-75 years). The tumors ranged in size from 0 mm (localized within the internal auditory canal) to 56 mm (28.3 ± 12.2 mm [mean ± SD]).
  
  
  RESULTS
  Gross-total resection (GTR) was performed in 41 (55%) of the 74 patients; subtotal resection ([STR]; 90-99%) in 25 (34%); and partial resection ([PR]; < 90%) in 8 (11%). Regrowth rates in the GTR, STR, and PR groups were 2.4% (1 of 41 cases), 52% (13 of 25), and 62.5% (5 of 8), respectively, and the times to regrowth ranged from 6 to 76 months (median 31.9 months). The regrowth-free survival curves differed significantly between the complete (GTR) and incomplete (STR and PR) resection groups. Eighteen (54.5%) of the 33 patients who underwent incomplete resection showed evidence of regrowth during follow-up. Univariate and multivariate analyses of various factors revealed that both the thickness of the residual tumor, based on MR imaging after surgery, and the MIB-1 index were positively related to residual tumor regrowth. The receiver operating characteristic curves, plotted for both the thickness of the residual tumor and the MIB-1 index, identified the optimal cutoff points for these values as 7.4 mm (sensitivity 83.3%, specificity 86.7%) and 1.6 (sensitivity 83.3%, specificity 66.7%), respectively.
  
  
  CONCLUSIONS
  Greater residual tumor thickness, based on MR imaging after the initial surgery, and a higher MIB-1 index are both important factors related to postoperative tumor regrowth in patients who have undergone incomplete VS resection. These patients require frequent neuroimaging investigation during follow-up to assure early detection of tumor regrowth.
authors.affiliation: Department of Neurosurgery, Brain Research Institute, University of Niigata, Niigata-City, Japan. mfuku529@bri.niigata-u.ac.jp
authors.forename: Masafumi
authors.initials: M
authors.lastname: Fukuda
authors.forename: Makoto
authors.initials: M
authors.lastname: Oishi
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Hiraishi
authors.forename: Manabu
authors.initials: M
authors.lastname: Natsumeda
authors.forename: Yukihiko
authors.initials: Y
authors.lastname: Fujii
mesh_terms: D000328:Adult; D000368:Aged; D003399:Craniotomy / Q000379:methods; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D053208:Kaplan-Meier Estimate; D008279:Magnetic Resonance Imaging; D008297:Male; D008866:Microsurgery / Q000379:methods*; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000175:diagnosis / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D018365:Neoplasm, Residual / Q000175:diagnosis / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D009464:Neuroma, Acoustic / Q000175:diagnosis / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D044767:Ubiquitin-Protein Ligases / Q000032:analysis; D055815:Young Adult
chemical_list: C513496:MIB1 ligase, human; D044767:Ubiquitin-Protein Ligases