LAUSR

Copyright C © 2018 by the Congress of Neurological Surgeons B rain peritumoral edema is a complex phenomenon, whose prognostic value is still debated with conflicting results both among the studies considering brain metastases and between the studies addressing primary brain cancers, such as high-grade gliomas (HGG). The current series1 specifically evaluated the effect of peritumoral edema on the survival of a subset of patients affected with posterior fossa metastases treated with surgical resection. The main finding of the study was that a higher edema volume to tumor volume ratio was associated with a significantly lower overall survival compared with those with a lower edema volume to tumor volume ratio. In general, the prognostic value of peritumoral edema of brain metastases is controversial. Spanberger et al2 demonstrated that large peritumoral edema is associated with better survival than small peritumoral edema. This conclusion might be due to smaller peritumoral edema being associated with higher propensity for brain-invasive growth, despite less angiogenesis and HIF1a expression. The survival benefit of large peritumoral edema was independent of the primary tumor type, although the role of molecular subtyping was not evaluated in the study. Kerschbaumer et al,3 however, found no correlation between extent of peritumoral edema and overall survival, but noted that edema is often responsible for the patients’ symptoms. In the case of glioblastoma (GBM), Lacroix et al4 found, in a large retrospective series of 416 patients, that while the degree of enhancement and tumor necrosis on preoperative magnetic resonance imaging (MRI) correlated with poorer survival, extent of peritumoral edema did not. Conversely, Schoenegger et al5 showed that patients affected with GBM with severe edema