Object. WHO Grade II and III intracranial meningiomas are uncommon, but they portend a significantly worse prognosis than their benign Grade I counterparts. The mainstay of current management is resection to obtain cytoreduction and histological tissue diagnosis. The timing and benefit of postoperative fractionated external beam radiation therapy and stereotactic radiosurgery remain controversial. The authors review the stereotactic radiosurgery outcomes for Grade II and III meningiomas.

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... : A comprehensive literature search was performed using PubMed to identify all radiosurgery series reporting the treatment outcomes for Grade II and III meningiomas. Case reports and case series involving fewer than 10 patients were excluded. Results. From 1998 to 2013, 19 radiosurgery series were published in which 647 Grade II and III meningiomas were treated. Median tumor volumes were 2.2-14.6 cm 3 . The median margin doses were 14-21 Gy, although generally the margin doses for Grade II meningiomas were 16-20 Gy and the margin doses for Grade III meningiomas were 18-22 Gy. The median 5-year PFS was 59% for Grade II tumors and 13% for Grade III tumors, which may have been affected by patient age, prior radiation therapy, tumor volume, and radiosurgical dose and timing. The median complication rate following radiosurgery was 8%. Conclusions. The current data for radiosurgery suggest that it has a role in the management of residual or recurrent Grade II and III meningiomas. However, better studies are needed to fully define this role. Due to the relatively low prevalence of these tumors, it is unlikely that prospective studies will be feasible. As such, well-designed retrospective analyses may improve our understanding of the effect of radiosurgery on tumor recurrence and patient survival and the incidence and impact of treatment-induced complications. keY WoRDS • intracranial meningioma • malignant meningioma • radiosurgery • Gamma Knife • CyberKnife • brain neoplasm 1 Abbreviations used in this paper: EBRT = external beam radiation therapy; GTR = gross-total resection; hpf = high-powered field; KPS = Karnofsky Performance Status; PFS = progression-free survival; SRS = stereotactic radiosurgery; WHO = World Health Organization. Unauthenticated | Downloaded 07/09/20 04:47 AM UTC * Tumor volume, margin dose, and follow-up are reported as median or mean values. CK = CyberKnife; GK = Gamma Knife; Gr = WHO grade; LINAC = linear accelerator; NR = not reported; pts = patients; RT = radiotherapy. † This series included 106 patients with WHO Grade I meningiomas and 5 patients with meningiomatosis. ‡ This series included 87 patients with WHO Grade I meningiomas. § This series included 168 patients with WHO Grade I meningiomas. ¶ This series included 286 WHO Grade I meningiomas. ** This series included 5 patients with WHO Grade I meningiomas and 12 WHO Grade II and III meningiomas treated with fractionated radiotherapy. † † This series included 424 WHO Grade I meningiomas and 536 tumors without histological diagnosis. ‡ ‡ This was the median margin dose for patients treated with Gamma Knife (n = 19). Some patients treated with CyberKnife (n = 13) received hypofractionated radiosurgery.