Metastatic Meningioma: A systematic review of incidence and risk factors

Background: Meningioma is the most common primary tumor of the central nervous system and has relatively good outcomes. Rarely, meningiomas metastasize and greatly reduce the likelihood of survival. Due to its infrequency, there is little information available to inform physicians whether a meningioma patient is at-risk for experiencing metastasis.Methods: We searched PubMed, Scopus, Embase, and Ovid for studies with intracranial meningiomas metastasizing to non-CNS locations. Case reports and studies with metastasis to the spinal cord were excluded. Primary tumors were characterized based on location, recurrence, histological grade, patient sex, and overall survival. Results: Our database search yielded 1,002 unique articles, of which 6 were included in the final review. The studies yielded a total of 546 patients with high-grade meningioma. Overall, there were 23 patients from this cohort that suffered metastasis of their primary tumor (4.2%). The majority of metastatic patients were female (65.0%), and 21 patients experienced recurrence of their primary tumor, along with metastasis (91.3%). Multiple risk factors were individually analyzed by studies, including skull base location, sinus invasion, and molecular characteristics.Conclusion: Metastatic meningioma is a rare but deleterious complication. Due to its infrequent incidence, there is a paucity of literature comparing risk factors for metastasis to guide clinical decision-making. Our study summarizes the current literature available on the overall incidence of metastasis in high-grade meningiomas and highlights multiple risk factors, both clinical and molecular, that future studies should characterize to provide a more comprehensive understanding of this rare pathology.