A brief history of ependymoma.

Ependymoma represents a biologically and clinically heterogeneous group of glial tumors that arise throughout the whole neuroaxis and in all age groups. Whereas intracranial ependymoma is usually found in children, adults suffer mostly from spinal cord ependymoma. In comparison to other neuro-oncological tumor entities, ependymoma has been largely understudied for decades. However, the recent years resulted in unprecedented progress with regard to the understanding of the biological underpinnings and clinical features of ependymoma. Here, we review the history of ependymoma research with a focus on the development of classification models throughout the years and a discussion of the most important clinical trials that have led to the current therapeutic standard, comprising maximal safe resection and, in most cases, radiotherapy. Critically, the evidence for effective drugs and chemotherapies in ependymoma is still sparse. However, these important questions may be soon addressed with the finalization of the currently unpublished last generation of multi-institutional trials in Europe (SIOP EP II) and Northern America (ACNS0831). Lastly, we discuss the current challenges in the field of ependymoma research and the necessary next steps toward the goal of findings cures for all types of ependymal tumors.