Cerebellopontine angle meningiomas: LINAC stereotactic radiosurgery treatment

Objectives

To evaluate the efficacy of treatment with linear accelerator-based stereotactic radiosurgery (LINAC) in cerebellopontine angle meningiomas.

Methods

We analyzed 80 patients diagnosed with cerebellopontine angle meningiomas between 2001 and 2014, treated with stereotactic radiosurgery (SRS), of whom 81.9% (n = 68) were women, with an average age of 59.1 years (32–79). SRS was applied as primary treatment in 83.7% (n = 67) and in 16.3% (n = 13) as an adjuvant treatment to surgery. SRS treatment was provided using LINAC (Varian 600, 6 MeV) with M3 micromultilamines (brainLab) and stereotactic frame. The average tumor volume was 3.12 cm³ (0.34–10.36 cm³) and the coverage dose was 14 Gy (12–16 Gy). We performed a retrospective descriptive analysis and survival analysis was performed with the Kaplan–Meier method and multivariate analysis to determine those factors predictive of tumor progression or clinical improvement.

Results

After an average follow-up period of 86.9 months (12–184), the tumor control rate was 92.8% (n = 77). At the end of the study, there was an overall reduction in tumor volume of 32.8%, with an average final volume of 2.11 cm³ (0–10.35 cm³). The progression-free survival rate at 5, 10 and 12 years was 98%, 95% and 83.3% respectively. The higher tumor volume (p = 0.047) was associated with progression. There was clinical improvement in 26.5% (n = 21) of cases and clinical worsening in 16.2% (n = 13). Worsening is related to the radiation dose received by the brainstem (p = 0.02). Complications were 8.7% (7 cases) of hearing loss, 5% (4 cases) of brain radionecrosis, and 3.7% (3 cases) of cranial nerve V neuropathy. Hearing loss was related to initial tumor size (p = 0.033) and maximum dose (p = 0.037). The occurrence of radionecrosis with the maximum dose (p = 0.037).

Conclusions

Treatment of cerebellopontine angle meningiomas with single-dose SRS using LINAC is effective in the long term. Better tumor control rates were obtained in patients with small lesions.