Postoperative radiotherapy for intracranial ependymoma: analysis of prognostic factors and patterns of failure

The long-term results of external beam radiotherapy following surgical resection in patients with intracranial ependymomas were evaluated to identify the prognostic factors and the pattern of recurrence. Between June 1961 and January 1999, 48 patients with intracranial ependymoma were treated with external beam irradiation with >40 Gy following surgery. Total doses of 40.5-63.4 Gy were delivered to the tumor site in 22-46 fractions over 33-101 days. Six patients with spinal deposit or positive cerebrospinal fluid cytology received whole spinal axis irradiation, and 4 patients received prophylactic spinal irradiation. The median follow-up of surviving patients was 110 months. The 10-year overall and relapse-free survival rates were 47% and 42%, respectively. In multivariate analysis, female gender, lower tumor grade and total resection were found to be associated with better relapse-free survival. Twenty of 26 recurrences developed at the primary tumor site (inside the irradiation field), two at the unirradiated cerebellum and spinal cord, and four at the spinal cord without intracranial failure. Only one of 34 patients with supratentorial tumors developed isolated spinal metastasis, whereas 3 of 14 patients with infratentorial tumors did so. Regarding the late neurotoxicity of radiotherapy, one of the 15 long-term (>4 years) survivors whose psychosocial status could be evaluated showed marked cognitive impairment. It was suggested that the use of new treatment strategies to improve local control would be warranted, and that prophylactic whole spinal axis irradiation appeared to be of more benefit in patients with infratentorial tumors than in those with supratentorial tumors.