The aim of this systematic review and meta-analysis was to study tumor characteristics and survival outcome in adult patients (>18 years old) with histological and/or radiological diagnosis of cystic glioblastoma-either IDH-wildtype glioblastoma or IDH-mutant grade IV astrocytoma (previously termed IDH-mutant glioblastoma-in comparison to those with glioblastomas that do not have a diagnosis of cyst or cystic components. This evidence concerns the gene IDH2 and astrocytoma (excluding glioblastoma).