Several articles report results with 0.5 -1 cm margins, and have suggested that with improved imaging and treatment planning, smaller margins such as those used by the EORTC are also appropriate for GTV to CTV expansion. The 2 cm expansions used in RTOG 0539 may result in much larger volumes of normal brain exposed to radiation. Is it therefore reasonable to treat patients with larger Simpson Grade 4, subtotally resected Grade II meningioma, with a 1 cm GTV to CTV expansion?

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High-risk Meningioma: Initial Outcomes From NRG Oncology/RTOG 0539. International Journal of Radiation Oncology, Biology, Physics. (2020). PMID: 31786276

Adjuvant postoperative high-dose radiotherapy for atypical and malignant meningioma: A phase-II parallel non-randomized and observation study (EORTC 22042-26042). Radiotherapy and Oncology. (2018). PMID: 29960684