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

Abstract

Objective: Stereotactic 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 (RT) may be employed to address these limitations. We performed a comparison of local control (LC) outcomes between 3 stereotactic techniques.

Methods: A retrospective review was performed of 543 consecutive patients with 613 histologically-proven World Health Organization grade I or radiographically-defined benign intracranial meningioma treated with SRS (median dose: 1250 cGy) (n = 211), fractionated SRS (2500 cGy in 500 cGy fractions) (n = 170), or conventionally fractionated stereotactic radiotherapy (FSRT) (median dose: 5022 cGy in ≤200 cGy fractions) (n = 232) in the definitive (n = 475) or postoperative (n = 138) setting between January 2008 and December 2021. Postoperative treatment was delivered upfront after a subtotal resection (n = 43) or for recurrent disease (n = 95).

Results: Median 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 ≥5 cc (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 fractionated SRS, and 97.5%/86.3% for FSRT. Dose escalation above 1250 cGy for SRS or above 5040 cGy for FSRT did not result in improved LC.

Conclusions: Durable LC was observed at long-term follow-up of intracranial meningioma treated with stereotactic radiosurgery and RT. LC outcomes were similar across the 3 fractionation regimens, suggesting that clinicians may tailor RT recommendations based on clinical factors without concern for reduced efficacy.

Keywords: Intracranial meningioma; Radiotherapy; Stereotactic radiosurgery.