Review of radiotherapy dose and volume for intracranial ependymoma

Radiotherapy (RT) is well established in the management of intracranial ependymoma (EP) and post-operative RT is employed for the majority of patients. There are no randomised trials of RT in EP and evidence for dose and volume relies on retrospective single institution series, usually comprising a heterogeneous mix of relatively small numbers of patients recruited over several decades.

The literature including RT dose and response data reported since the early 1990s was reviewed.

Five-year overall survival (OS) ranges from 40 to 79%. There is some evidence of a dose response relationship from <45 Gy to >50 Gy. In the majority of series outcome is related to WHO grade and extent of resection. There is no evidence of benefit for 'prophylactic' craniospinal RT (CSRT). In all series there is a significant risk of local recurrence, usually within the target volume. Early results of conformal RT have suggested that a margin for CTV of 1 cm around the post-operative tumour bed and any residual GTV is feasible.

The main aims of future studies will be to maximise the number of patients achieving complete resection, and RT dose escalation. Hyperfractionated radiotherapy (HFRT) has been employed in some studies and results are awaited. The role of CSRT needs to be evaluated further for patients presenting with leptomeningeal metastases. Multi-institutional and international studies are necessary to improve understanding of the clinical behaviour, biology and management of EP.