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Updated: May 19, 2026
Proton Therapy Delivery and Its Clinical Application in Select Solid Tumor Malignancies
Published on: February 6, 2019
Dose Escalation with Intensity-Modulated Proton Therapy for Patients with High-Risk Meningiomas - Results from a
Felix Ehret1,2,3,4, Nora K Horick5, Beow Y Yeap2,5
1Department of Radiation Oncology, Massachusetts General Hospital, Mass General Brigham, Boston, Massachusetts.
Purpose:
Outcomes for grade 2 and 3 meningiomas are poor. A few studies suggest a benefit from radiotherapy dose escalation. This trial evaluates the safety and efficacy of dose escalation with intensity-modulated proton therapy (IMPT) for grade 2 and 3 meningiomas.
Patients And Methods:
This prospective single-arm phase I trial enrolled patients with grade 2 meningioma with residual disease or recurrence or patients with grade 3 meningioma after gross total resection. Patients underwent dose-escalated IMPT to 66 Gy relative biological effectiveness [Gy(RBE)] for grade 2 gross disease and 63 Gy(RBE) for grade 3 tumor beds. The primary endpoint was acute dose-limiting toxicity (DLT). Secondary endpoints included progression-free survival (PFS), overall survival (OS), and late toxicity.
Results:
Twenty-one patients with 16 grade 2 and 5 grade 3 meningiomas were enrolled and treated between 2016 and 2023. The median clinical and radiographic follow-up periods were 3.4 and 3.2 years, respectively. No DLT was observed. Five new late grade 3 toxicities occurred in four patients. Three treatment failures were observed in two grade 2 and one grade 3 tumors. Two deaths occurred in patients with grade 2 meningiomas. The 1-, 2-, and 3-year PFS rates were 100%, 95%, and 88.2%, respectively. The corresponding OS rates were 100%, 95%, and 95%, respectively.
Conclusions:
This first prospective trial investigating dose-escalated IMPT for high-grade meningiomas demonstrated a favorable early safety profile and clinical outcomes. Phase II and III studies are warranted to confirm the superiority of dose escalation for high-grade meningiomas.
