Chromosomal alterations, prognostic factors, and targeted molecular therapies for malignant meningiomas

Meningiomas are the second most common intracranial neoplasm in adults and originate from arachnoidal cap cells. Malignant meningiomas are resistant to conventional treatments such as surgery, chemotherapy, and radiotherapy. Unlike benign meningiomas, atypical and anaplastic tumors generally display more complex karyotypes associated with aggressive behavior. While these chromosomal anomalies are associated with greater malignancy in meningiomas, the specific genes involved remain unknown. Malignant meningiomas are characterized by increased tumor aggressiveness, rapid recurrence, local invasion, atypical histological appearance, and a high mitotic index. Potential prognostic factors include extent of resection, treatment with radiotherapy or stereotactic radiosurgery, Ki-67/MIB-1 labeling index, p53 overexpression, percentage of tumor cells in the S-phase, telomerase activity, and numerous genetic expression profiles. A greater understanding of prognostic factors and molecular markers involved in critical signaling pathways may aid in the identification of novel therapeutic targets. As such, further studies are needed to establish reliable prognostic factors and develop more effective treatments for malignant meningiomas. (C) 2012 Elsevier Ltd. All rights reserved.