Nationwide Brain Tumor Registry-based Study of Adult Intracranial Ependymoma in Japan

Ependymoma, a rare neuroepithelial malignancy of the central nervous system, affects both children and adults and may occur anywhere along the neuroaxis. This study aimed to analyze the treatment outcomes of adult intracranial ependymoma cases in Japan using data from the Brain Tumor Registry of Japan between 2001 and 2008. The dataset comprised 169 eligible patients after applying exclusion criteria, such as subependymoma and myxopapillary ependymoma cases. Patient data encompassed demographic details, tumor classification, treatment strategies, extent of resection, WHO grade, and survival outcomes.Kaplan-Meier and multivariate Cox proportional hazards analyses identified key prognostic factors influencing overall survival and progression-free survival. Gross total resection and near-total resection were associated with better outcomes, while EOR less than 95% and preoperative Karnofsky performance status score below 70 were significantly correlated with poorer OS. WHO grade 2 tumors were more prevalent in posterior fossa and demonstrated better survival outcomes than grade 3 tumors in univariate analyses. However, WHO grade did not remain significant in multivariate analysis when adjusted for tumor location.This study highlights the critical impact of radical resection on ependymoma prognosis. While CNS WHO grade showed correlations with tumor location and survival, its role in predicting outcomes remains uncertain and may depend on molecular subtypes. Updated molecular classifications are recommended for future research.