Van den Bent’s group has confirmed in a series of 228 LGGs that both EOR and tumor molecular class exert independent prognostic roles [16]; furthermore, especially in the IDH mutated astrocytomas, a post-operative volume of 0.5–1 cm3 was sufficient to affect prognosis negatively, suggesting the possible importance of a second surgery in these patients. This evidence concerns the gene IDH1 and astrocytoma (excluding glioblastoma).