Proton therapy for atypical meningiomas.

Area of Science:

• Oncology
• Radiation Oncology
• Neurosurgery

Background:

• Atypical meningiomas (WHO grade 2) are challenging tumors requiring effective treatment strategies.
• Proton therapy offers precise radiation delivery, potentially minimizing toxicity.
• Clinical outcomes of proton therapy for atypical meningiomas are not well-established.

Purpose of the Study:

• To evaluate the clinical outcomes of proton therapy in patients with World Health Organization grade 2 meningiomas.
• To assess the efficacy of proton therapy in terms of local control and dissemination.
• To explore the relationship between radiation dose and treatment outcomes.

Main Methods:

• Retrospective analysis of 22 patients with atypical meningiomas treated with proton therapy between 2005 and 2013.
• Patients received a median dose of 63 Gy (RBE) as adjuvant therapy or for recurrent/progressive disease.
• Clinical outcomes including local control, neuraxis dissemination, and distant metastases were assessed.

Main Results:

• All patients remained alive at a median follow-up of 39 months.
• The 5-year local control rate was 71.1%.
• Higher radiation doses (>60 Gy RBE) were associated with significantly improved local control (87.5% vs. 50.0%, p=0.038).
• Rates of neuraxis dissemination and distant metastases were low (5% and 6.2%, respectively).
• One case of radiation necrosis was observed in a patient with prior cranial irradiation.

Conclusions:

• Fractionated proton therapy demonstrates favorable tumor control for grade 2 meningiomas.
• Radiation doses exceeding 60 Gy (RBE) appear to enhance local control.
• Prospective studies are warranted to determine optimal radiation doses for high-grade meningiomas.