Outcome After Protontherapy for Progression or Recurrence of Surgically Treated Meningioma.

Background: To assess the outcome after meningioma surgery and protontherapy (PT).

Methods: We processed the French Système National des Données de Santé database to retrieve appropriate cases of meningiomas operated and irradiated between 2008 and 2017. Survival methods were implemented.

Results: One hundred ninety-three patients who received PT after meningioma surgery over a 10-year period were identified. Of the 193 patients, 75.6% were female. Median age at surgery was 50 years (interquartile range [IQR] 41-62). The median number of PT fractions was 31 (IQR 30-39) given over a median duration of 52 days (IQR 44-69). Fourteen patients (7.3%) also received photon radiotherapy and six patients (3.1%) stereotactic radiosurgery. Median follow-up was 4.4 years (IQR 3.86-4.71). Five-year progression-free survival (PFS) rate was 69% (95% confidence interval [CI] 62.1-76.6). For benign, atypical, and malignant meningioma, 5-year PFS rates were 71.5% (95% CI 64.4-79.4), 55.6% (95% CI 32.5-95), and 35.6% (95% CI 12.8-98.9), respectively (<0.01). In the adjusted regression, tumour location (hazard ratio [HR]=0.1, 95% CI 0.05-0.22, <0.001), aggressive meningioma (HR=2.26, 95% CI 1.1-4.66, =0.027), and the need of cerebrospinal fluid (CSF) insertion for hydrocephalus (HR=3.51, 95% CI 1.32-9.31, =0.012) remained significantly associated to the PFS. All grades considered, 5-year overall survival (OS) rates was 89.7% (95% CI 84.6-95.1). For benign, atypical, and malignant meningioma, 5-year OS rates were 93% (95% CI 88.7-97.4), 76.4% (95% CI 51.4-100), and 44.4% (95% CI 16.7-100), respectively (<0.01). In the multivariable regression, an older age above 70 years (HR=5.95, 95% CI 2.09-16.89, <0.001) associated to a high level of comorbidities (HR=5.31, 95% CI 1.43-19.78, =0.013) and a malignant meningioma (HR=5.68, 95% CI 1.54-20.94, =0.009) remained significantly associated to a reduced OS.

Conclusion: Five-year PFS and OS after meningioma surgery and PT is favourable but impaired for older patients with high level of morbidities, tumour of the convexity, malignant histopathology and for those requiring CSF shunting. Further inclusion and prolonged follow-up is required to assess other predictors such as sex, tumour volume, or given dose.