Long-term outcome of high-precision radiotherapy in patients with brain stem gliomas: results from a difficult-to-treat patient population using fractionated stereotactic radiotherapy.

INTRODUCTION: To assess long-term outcome in 85 patients with brain stem gliomas treated with fractionated stereotactic radiation therapy (FSRT). PATIENT AND METHODS: Thirty-nine patients were females, and 46 were males. Median age at primary diagnosis was 26 years. Thirty-one patients were younger than 18 years. Histopathological examination confirmed a low-grade glioma in 57 patients. Of the group of high-grade gliomas, six were anaplastic astrocytomas, and two were classified as glioblastoma. Radiation therapy was performed as FSRT. The median target volume was 101 ml. We applied a median dose of 54 Gy in conventional fractionation of 1.8 Gy. In seven of 85 patients (8%) FSRT was performed as re-irradiation.
RESULTS: The median follow-up time was 42 months. Median overall survival (OS) was 81 months. OS rates were 77% at 12 months, 70% at 24 months, and 63% at 36 months. Significant impact on OS could be shown for pilocytic histology, age, neurosurgical resection as well as for the presence of cyst on MR-imaging. Median progression-free survival (PFS) after FSRT was 52 months. PFS rates at 12 months were 70%, and 63% and 58% at 24 and 36 months, respectively. Histology, partial neurosurgical resection and the duration of symptoms could be identified as significant prognostic factors.
CONCLUSION: Long-term outcome of FSRT in patients with brain stem gliomas is acceptable with low rates of side effects. Significant impact on outcome could be shown for histology, age, extent of neurosurgical resection as well as for cyst formation. No dose-response relationship could be observed.