P.139 Pediatric posterior fossa ependymoma recurrence in a molecularly defined cohort – Clinical, demographic, and surgical factors associated with outcome

Abstract

Background: Pediatric posterior fossa ependymoma contributes to morbidity and mortality in children. Following gross total resection and adjuvant radiotherapy, there is a known risk of local recurrence that portends a dismal prognosis. We sought to characterize survival in a molecularly defined cohort with an emphasis on recurrence patterns that influence outcome. Methods: This study was approved by the Ethics Board of the Hospital for Sick Children. We performed a twenty-year single-center retrospective study to identify clinical, demographic and treatment characteristics of patients with pathologically diagnosed posterior fossa ependymoma. Results: There were 60 patients identified that underwent primary resection. Recurrence rate in the cohort was 48% with 29 cases of recurrent ependymoma occurring at a mean time of 24 months after index surgery. No mortalities were observed among patients undergoing primary resection without recurrent disease. Median cohort survival was 12.3 years in the primary cohort and and 6.32 years among patients recurrent ependymoma. Recurrent disease was significantly associated with worse overall survival after multivariate analysis (HR = 0.024). Conclusions: We highlight overall survival and factors influencing mortality in pediatric posterior fossa ependymoma. Recurrent disease confers a worse prognosis. We describe for the first time survival trends following local and distant recurrences managed through multiple resections.