Cyberknife stereotactic radiosurgery for treatment of atypical (WHO grade II) cranial meningiomas.
BACKGROUND
The optimal management of subtotally resected atypical meningiomas is unknown.


OBJECTIVE
To perform a retrospective review of patients with residual or recurrent atypical meningiomas treated with stereotactic radiosurgery (SRS).


METHODS
Twenty-five patients were treated, either immediately after surgery (n = 15) or at the time of radiographic progression or treatment failure (n = 10). SRS was delivered to with a median marginal dose of 22 Gy (range, 16-30) in 1 to 4 fractions (median, 1), targeting a median tumor volume of 5.3 cm³ (range, 0.3-26.0).


RESULTS
With a median follow-up time of 28 months (range, 3-67), the 12-, 24-, and 36-month actuarial local and regional control rates for all patients were 94%, 94%, 74%, and 90%, 90%, 62%, respectively. There were 2 cases of radiation toxicity. On univariate analysis, the number of recurrences before SRS (P = .046), late SRS (ie, waiting until tumor progression to initiate treatment) (P = .03), and age at treatment ≥ 60 years (P = .01) were significant predictors of recurrence. Of the 20 radiation-naïve patients, 2 patients failed with the targeted lesion and 3 elsewhere in the resection bed, resulting in 12-, 24- and 36-month actuarial local and regional control rates of 100%, 100%, 73% and 93%, 93%, 75%, respectively. The overall locoregional control rates at 12, 24, and 36 months were 93%, 93%, and 54%, respectively.


CONCLUSIONS
Irradiation of the entire postoperative tumor bed may not be necessary for the majority of patients with subtotally resected atypical meningiomas. Patients in this series achieved outcomes comparable to that of historical control rates for larger volume, conventionally fractionated radiotherapy.
Choi
Clara Y H
CY
Department of Neurosurgery, Stanford University Medical Center, Stanford, California, USA. cyhchoi@stanford.edu
Soltys
Scott G
SG
Gibbs
Iris C
IC
Harsh
Griffith R
GR
Jackson
Paul S
PS
Lieberson
Robert E
RE
Chang
Steven D
SD
Adler
John R
JR
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001932:Brain Neoplasms / Q000175:diagnosis / Q000601:surgery*; D005260:Female; D006801:Humans; D008297:Male; D008577:Meningeal Neoplasms / Q000175:diagnosis / Q000601:surgery*; D008579:Meningioma / Q000175:diagnosis / Q000601:surgery*; D008875:Middle Aged; D016634:Radiosurgery / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult