A systematic review of extraneural meningioma metastasis: timing, evolution and outlook.

Purpose: Extraneural meningioma metastasis is a rare occurrence and may pose a clinical challenge due to its unclear prognosis. In this systematic review, we analyze patient demographics, clinical characteristics, management strategies, and outcomes.

Methods: PubMed, EMBASE, Scopus, Cochrane, and Web of Science databases were searched from inception to February 23, 2024 for cases of metastatic meningioma according to PRISMA guidelines. Descriptive statistics, Mann-Whitney U test, Fisher's exact tests, Kaplan-Meier curves, and log-rank tests were used for selected analyses.

Results: A total of 288 patients (52% male) were included with an average age of 49 years at meningioma diagnosis. Tumors were distributed across WHO grade 1 (38%), 2 (36%), and 3 (26%). Most patients experienced intracranial recurrence (79%) and mean time to first metastasis was approximately 8 years. No change in WHO grade between primary and metastasis was observed for most cases (65%). Treatment of the initial metastasis was most often with surgery (43%), chemotherapy (20%), or no treatment (14%). Half of the patients were alive (50%) with an average follow-up of 3 years following metastasis. Overall median survival was 36 months for the entire cohort. This differed significantly between WHO grade 1 versus 2/3 meningioma primaries (168 vs. 15 months, p < 0.005).

Conclusion: Metastatic meningioma appears to be associated with more positive prognosis than other brain tumor types with extra-neural metastasis or metastasis in general. This is particularly true for cases arising from a WHO grade 1 meningioma.