An evidence-based treatment algorithm for the management of WHO Grade II and III meningiomas.

The management of WHO Grade II "atypical" meningiomas (AMs) and Grade III "malignant" meningiomas (MMs) remains controversial and under-investigated in prospective studies. The roles of surgery, radiation therapy, radiosurgery, and chemotherapy have been incompletely delineated. This has left physicians to decipher how they should treat patients on a case-by-case basis. In this study, the authors review the English-language literature on the management and clinical outcomes associated with AMs and MMs diagnosed using the WHO 2000/2007 grading criteria. Twenty-two studies for AMs and 7 studies for MMs were examined in detail. The authors examined clinical decision points using the literature and concepts from evidence-based medicine. Acknowledging the retrospective nature of the studies concerning AM and MM, the authors did find evidence for the following clinical strategies: 1) maximal safe resection of AM and MM; 2) active surveillance after gross-total resection of AM; 3) adjuvant radiation therapy after subtotal resection of AM, especially in the absence of putative radioresistant features; and 4) adjuvant radiation therapy after resection of MM.