Impact of Fractionation Regimen on Local Control Following Frameless Linear Accelerator-Based Image-Guided Stereotactic Radiosurgery and Radiotherapy for Intracranial Meningioma

Abstract

ObjectivesStereotactic radiosurgery (SRS) is an established treatment for intracranial meningioma, yet this approach is often precluded by tumor size or proximity to critical structures. Fractionated radiotherapy may be employed to address these limitations. We performed a comparison of local control (LC) outcomes between three stereotactic techniques. MethodsA retrospective review was performed of 543 consecutive patients with 613 histologically-proven WHO grade I or radiographically-defined benign intracranial meningioma treated with SRS (median dose: 1250cGy) (n=211), fractionated SRS (FSRS) (2500cGy in 500cGy fractions) (n=170), or conventionally fractionated stereotactic radiotherapy (FSRT) (median dose: 5022cGy in <200cGy fractions) (n=232) in the definitive (n=475) or post-operative (n=138) setting between January 2008 and December 2021. Post-operative treatment was delivered upfront after a subtotal resection (n=43) or for recurrent disease (n=95). ResultsMedian follow-up per lesion was 8.0 years. LC for all lesions at 5/10/14 years was 97.4%/86.8%/86.8%. Base of skull location (p=0.01), tumor volume >5cc (p=0.01), and recurrent disease (p=0.02) were associated with inferior LC. No difference was observed in LC by fractionation regimen; LC at 5/10 years was 97.3%/85.7% for SRS, 97.5%/89.1% for FSRS, and 97.5%/86.3% for FSRT. Dose escalation above 1250cGy for SRS or above 5040cGy for FSRT did not result in improved LC. ConclusionsDurable LC was observed at long-term follow-up of intracranial meningioma treated with stereotactic radiosurgery and radiotherapy. LC outcomes were similar across the three fractionation regimens, suggesting that clinicians may tailor radiotherapy recommendations based on clinical factors without concern for reduced efficacy.