title: Stereotactic proton beam therapy of skull base meningiomas.
abstract: OBJECTIVE
  To review outcomes for patients with skull base meningiomas treated using the stereotactic proton beam at the National Accelerator Center (NAC), Republic of South Africa.
  
  
  METHODS
  Since 1993, 27 patients with intracranial meningiomas have been treated stereotactically with protons at NAC. Of those, 23 were located on the skull base, were large or had complex shapes, and were treated with radical intent. Both stereotactic radiotherapy (SRT, 16 or more fractions) and hypofractionated stereotactic radiotherapy (HSRT, 3 fractions) were used. Eighteen patients underwent proton HSRT, while 5 patients were treated with SRT. The mean target volume for the HSRT group was 15.6 cm(3) (range 2.6-63 cm(3)). The mean ICRU reference dose was 20.3 cobalt Gray equivalent (CGyE), and the mean minimum planning target dose was 16.3 CGyE. The mean clinical and radiologic follow-up periods were 40 and 31 months respectively. The mean volume in the SRT group was 43.7 cm(3), with ICRU reference doses ranging from 54 CGyE in 27 fractions to 61.6 CGyE in 16 fractions.
  
  
  RESULTS
  In the HSRT group, 16/18 (89%) of patients remained clinically stable or improved, while 2/18 (11%) deteriorated. Radiologic control was achieved in 88% of patients, while 2 patients had a marginal failure. Among the 5 SRT patients, 2 were clinically better, and 3 remained stable. All SRT patients achieved radiologic control. Three patients (13%), 2 of them in the HSRT group, suffered permanent neurologic deficits. Analyzing different dose/fractionation schedules, an alpha/beta value of 3.7 Gy for meningiomas is estimated.
  
  
  CONCLUSIONS
  Proton irradiation is effective and safe in controlling large and complex-shaped skull base meningiomas.
authors.affiliation: Department of Radiation Oncology, Tygerberg Hospital, Tygerberg, South Africa. fvnacpn@iafrica.com
authors.forename: F J
authors.initials: FJ
authors.lastname: Vernimmen
authors.forename: J K
authors.initials: JK
authors.lastname: Harris
authors.forename: J A
authors.initials: JA
authors.lastname: Wilson
authors.forename: R
authors.initials: R
authors.lastname: Melvill
authors.forename: B J
authors.initials: BJ
authors.lastname: Smit
authors.forename: J P
authors.initials: JP
authors.lastname: Slabbert
mesh_terms: D000328:Adult; D000368:Aged; D003389:Cranial Nerve Diseases / Q000209:etiology; D005260:Female; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000601:surgery*; D008579:Meningioma / Q000601:surgery*; D008875:Middle Aged; D061766:Proton Therapy; D011522:Protons / Q000009:adverse effects; D016634:Radiosurgery / Q000009:adverse effects / Q000379:methods*; D019291:Skull Base; D016896:Treatment Outcome
chemical_list: D011522:Protons