Extraventricular site indicates higher grade but better prognosis in adult supratentorial ependymomas: a 14-year single-center retrospective cohort

Supratentorial extraventricular ependymoma (STEE) and supratentorial intraventricular ependymoma (STIE) are two subsets of supratentorial ependymoma (SE). These two subsets have similar gene features and only differ in original sites: STEE occurs in the brain parenchyma, and STIE is located in ventricles and surrounded by cerebral spinal fluid. The present study aims to depict the diversities of these two subsets and elucidate the potential effects of the anatomic site on the tumor with the same type, grade, and molecular features. Sixty-six consecutive adult SE patients from 2008 to 2021 were enrolled in our study. Clinical data, pathological features, and long-term outcomes were analyzed retrospectively. Results demonstrated that adult STEE presented with a higher proportion of WHO grade 3 ( P = .028) and higher Ki-67 index (≥10%) ( P = .019) compared to adult STIE. Survival analysis demonstrated that patients of grade 3 STEE exhibited a significantly longer overall survival (OS) than patients of grade 3 STIE (median OS, 24.4 months vs. 13.0 months; P = .004). Grade 2 (hazard ratio (HR) = 0.217; P < .001) and gross total resection (GTR) (HR = 0.156; P < .001) were identified as favorable prognostic factors for all adult SE. The STEE was also associated with a lesser hazard of death for patients of grade 3 on multivariate analysis (HR = 0.263; P = .047). These findings suggested that the extraventricular site was an indicator for higher grade and better prognosis in adult supratentorial ependymoma.