AstrocytomaGliomaBrain NeoplasmsNimustineGlioblastomaNitrosourea CompoundsSupratentorial NeoplasmsOligodendrogliomaBrain Stem NeoplasmsHypothalamic NeoplasmsSpinal Cord NeoplasmsEpendymomaNeoplasm GradingCentral Nervous System NeoplasmsMeningiomaImmunohistochemistryOptic Nerve NeoplasmsIsocitrate Dehydrogenase