Fractionated Radiotherapy With Stereotactic Radiosurgery Boost Controls Gross Disease in Grade 2 Meningioma.

Objective: Opportunity exists for improved local control rates of grade 2 meningiomas that recur despite maximal surgical resection and adjuvant fractionated radiotherapy (RT). We describe a dose escalation strategy of increasing the total tumor radiation dose by adding a stereotactic radiosurgery (SRS) boost targeting gross disease to fractionated RT.

Methods: A single-institution retrospective cohort of patients from 2009-2023 with grade 2 meningioma treated with surgical resection, fractionated RT, and SRS boost were evaluated for baseline characteristics, local disease control, and adverse events (AE).

Results: Fourteen meningioma patients were included. Ten patients (71.4%) underwent radiosurgery at initial diagnosis, while 4 patients (28.6%) were treated for recurrent disease. The median fractionated dose was 54 Gy, while the median dose for SRS was 7.5 Gy. Among the 13 patients with follow-up available, median follow-up was 34 months. Three patients (23%) had treatment failures; however, none occurred within the SRS volume and 2 thirds occurred in patients treated for recurrent disease. Eighteen-month progression-free survival was 92.3%, while 18-month overall survival was 100%. Most patients experienced no or mild AEs; however, 3 patients (23%) experienced a high-grade (Common Terminology Criteria for Adverse Events v5.0 grade ≥3) AE including radiation necrosis, seizures, and cognitive decline.

Conclusions: We found 100% in-field local control at 3 years from an SRS boost to fractionated RT targeting gross disease with an acceptable toxicity profile, suggesting this may be an effective and improved adjuvant treatment strategy in patients with grade 2 meningioma.