title: Management of non-benign meningiomas with Gamma Knife radiosurgery.
abstract: OBJECTIVE
  Results of Gamma Knife radiosurgery (GKS) were retrospectively evaluated in 16 patients with histologically confirmed atypical and anaplastic intracranial meningiomas.
  
  
  METHODS
  There were nine men and seven women (mean age 61.0 years). Atypical meningiomas were diagnosed in nine cases and anaplastic meningiomas in seven. In nine patients there was malignant transformation of a tumor that had initially proved to be benign. In total, 21 radiosurgical procedures were performed. The mean tumor volume at the time of GKS was 7.1 cm3. The mean marginal and maximum irradiation doses were 18.8 and 37.0 Gy, respectively. The mean length of follow-up after treatment was 37.1 months.
  
  
  RESULTS
  Of 21 radiosurgical procedures, 6 (29 %) led to stabilization of tumor growth during the mean follow-up of 40.5 months. It was significantly associated with small lesion volume (P = 0.02), and greater marginal (P = 0.04) and maximum (P = 0.02) irradiation doses. Seven patients underwent eight surgical resections of a progressing tumor during the mean period of 26.1 months after irradiation. Five patients (31 %) died because of tumor progression within the average time period of 16.8 months after GKS. Overall, at the time of the last follow-up just two patients (13 %) had no evidence of tumor regrowth, and only three patients (19 %) maintained good activities of daily living during 12, 59, and 69 months, respectively, after radiosurgery.
  
  
  CONCLUSIONS
  GKS has limited efficacy in cases of non-benign meningioma. Better tumor control rates can be attained for small neoplasms treated with greater marginal and maximum irradiation doses.
authors: Faculty of Advanced Techno-Surgery, Institute of Advanced Biomedical Engineering and Science, TWIns, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo, 162-8666, Japan. manabu97@abmes.twmu.ac.jp
authors: Manabu
authors: M
authors: Tamura
authors: Kenji
authors: K
authors: Kubo
authors: Ryuji
authors: R
authors: Okita
authors: Mitsuhiro
authors: M
authors: Ogura
authors: Naoyuki
authors: N
authors: Nakao
authors: Yuji
authors: Y
authors: Uematsu
authors: Toru
authors: T
authors: Itakura
authors: Motohiro
authors: M
authors: Hayashi
authors: Yoshihiro
authors: Y
authors: Muragaki
authors: Hiroshi
authors: H
authors: Iseki
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000601:surgery*; D008579:Meningioma / Q000601:surgery*; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011183:Postoperative Complications / Q000473:pathology; D011832:Radiation Injuries / Q000473:pathology; D016634:Radiosurgery / Q000379:methods*; D012189:Retrospective Studies