Comparison of outcomes of gamma knife radiosurgery for secondary and de novo grade 2 meningiomas: a single-center retrospective study

Objective The purpose of this study was to compare outcomes between secondary and de novo grade 2 meningiomas undergoing Gamma Knife radiosurgery (GKRS). Methods Eighteen patients, including secondary grade 2 meningioma group (n = 6) and de novo grade 2 meningioma group (n = 12), treated with GKRS were enrolled in this single-center retrospective study. Results The median tumor volume was 23.4 (range, 5.5–104.0) ml and 9.4 (range, 0.4–24.9) ml in secondary and de novo grade 2 meningioma group respectively ( p  = 0.061). Ten patients (55.6%) experienced radiological progression with a median follow-up time of 35.7 (range, 9.4-138.2) months. The median time to radiological progression was 34.5 (range, 14.5–97.7) months. The radiological progression-free survival (PFS) was 74%, 55%, and 15% at 2, 3 and 5 years respectively. The radiological PFS at 2 and 3 years was 60% and 20%, 82% and 82% in secondary and de novo grade 2 group respectively. Secondary grade 2 meningiomas were significantly related with poorer radiological PFS in univariate analysis ( p  = 0.021). Nine patients (50%) occurred clinical progression in the study, including headache (n = 7), cranial nerve dysfunction (n = 5), seizure (n = 1) and extremity weakness (n = 1). Secondary grade 2 meningiomas were significantly related with clinical progression in univariate analysis (p = 0.045). Conclusions Secondary grade 2 meningiomas had a shorter radiological and clinical PFS after GKRS than de novo grade 2 meningiomas. Secondary grade 2 meningiomas were an independent risk factor for poor prognosis after GKRS.