Staged Gamma Knife Radiosurgery for Large Skull Base Meningiomas

Area of Science:

• Neurosurgery
• Radiation Oncology
• Oncology

Background:

• Skull base meningiomas larger than 4 cm present treatment challenges.
• Low-dose Gamma Knife radiosurgery (GKS) has shown promise for meningioma treatment with reduced morbidity.
• Volume-staged GKS is a strategy to manage larger tumors incrementally.

Purpose of the Study:

• To describe the treatment strategy and outcomes of volume-staged, low-dose GKS for large skull base meningiomas (>4 cm).
• To evaluate the efficacy and safety of this approach in a cohort of patients with large meningiomas.

Main Methods:

• Retrospective review of 27 patients with large skull base meningiomas (WHO grade I or imaging-diagnosed) treated with volume-staged GKS between 1995 and 2018.
• Tumors were located in various skull base regions, with mean diameters ranging from 31 to 47.8 mm.
• Prescribed radiation doses were 8-12 Gy, with treatment intervals of 3-9 months between GKS sessions.

Main Results:

• Tumor volume decreased in 37.5%, remained stable in 37.5%, and increased in 25% of patients.
• The actuarial progression-free local control rates were 88% at 3 years, 78% at 5 years, and 70% at 10-15 years.
• Neurological status improved in 12.5%, remained unchanged in 66.5%, and deteriorated in 21%; permanent radiation injury occurred in 4%.

Conclusions:

• Volume-staged Gamma Knife radiosurgery is a useful treatment modality for large skull base meningiomas (>4 cm).
• The technique provides long-term tumor control with acceptable rates of neurological morbidity and treatment-related injury.