Approximately 15-20% of meningiomas are atypical, meaning that the tumor cells do not appear typical or normal. Atypical meningiomas are neither malignant (cancerous) nor benign, but may become malignant. Grade II atypical meningiomas also tend to recur and grow faster.
retrospective series supports the observation that postoperative radiotherapy likely results in lower recurrence rates of gross totally resected atypical meningiomas. Although a multicenter prospective trial will ultimately be needed to fully define the role of radiotherapy in managing gross totally resected atypical meningiomas 1)
Jenkinson MD, Weber DC, Haylock BJ, Mallucci CL, Zakaria R, Javadpour M.Radiotherapy versus Observation following surgical resection of Atypical Meningioma (the ROAM trial). Neuro Oncol. 2014 Jul 19. pii: nou149. [Epub ahead of print] PubMed PMID: 25038504.