gms | German Medical Science

Objective: Atypical and malignant meningiomas are associated with a poorer prognosis than benign meningiomas mostly due to recurrence after resection. While the role of surgery as a primary treatment modality is well established, the role of adjuvant radiosurgery regarding efficacy still has to be elucidated.

Method: The medical records and imaging of 42 patients with histologically proven atypical and anaplastic meningioma treated with radiosurgery in particularly Gamma Knife and/or Cyber Knife between 1996 and 2014 were reviewed retrospectively. Patient demographics, history of disease, treatment characteristics and radiographic data (MRI-imaging and DOTATATE-PET-CT imaging) were analysed. Primary endpoint was clinical outcome according to progression-free-survival.

Results: 42 patients were treated with stereotactic radiosurgery (76 treatment sessions). Mean tumor volume was 9.45 cm³ (range 0.6-51.4 cm³). Mean age at treatment was 56.2 (range, 26-93 years). Median duration of follow-up was 48.8 months. Treatment failures were determined by serial magnetic resonance imaging. Mean PFS was 28.2 months (range 3-120 months). The median 3-year PFS was 64 % for WHO Grade II tumors and 0% for WHO Grade III tumors. The median complication rate following radiosurgery was 6,6%.

Spinal manifestation was detected in 1 patient with atypical meningioma. Pulmonary metastasis was seen in 1 patient with anaplastic meningioma. Eight patients (19%) died (5 patients with diagnosed WHO Grad II meningioma and 3 patients with diagnosed WHO III meningioma) with a mean overall survival of 88.4 months for WHO Grad II meningioma and 10 months for WHO Grad III patients. At last follow-up, 13 patients had no evidence of recurrent tumor growth.

Conclusions: Similar to our data, two recently published studies on smaller groups of SRS-treated WHO Grade II meningiomas showed progression-free survival (PFS) rates of 70.0% after 3 years and 40% after 5 years. Due to the low complication rate (6,6% in our series), we consider SRS as a safe treatment modality to achieve local tumor control. Histological grading (WHO Grad III) was the most important prognostic factor.