In our irradiated cohort, in univariate analysis we found significant differences of PFS stratified by WHO grade I versus WHO grade II meningiomas (p = 0.026), estimated MIB-1 staining below 4% (p = 0.019), primary or adjuvant radiotherapy versus salvage treatment (p = 0.003) and the localization (in favour of skull base and optic nerve sheath meningiomas compared to other localizations, p = 0.007). This evidence concerns the gene MIB1 and meningioma.