Radiotherapy for intracranial and spinal ependymomas. A retrospective analysis.

BACKGROUND: The low incidence of ependymomas results in limited treatment experience. While standard therapy consists of surgery and postoperative radiotherapy, irradiation techniques are still subject to discussion. We report the experience from Münster over the last 35 years. PATIENTS AND METHODS: Since 1961, 25 evaluable patients with ependymoma were irradiated in Münster: 17 intracranial and 8 spinal tumors. Fourteen of 25 patients underwent subtotal resection. Fifteen of 25 patients were treated by local irradiation, 10 of 25 with large-field techniques (whole-brain/cranio-spinal irradiation) and an additional tumor boost. The median tumor dose amounted to 50 Gy (16 to 65 Gy). Sites of recurrence were analyzed and correlated with the irradiated region.
RESULTS: Twelve recurrences were observed. Six of 12 could be exactly related to the irradiation portals and were found well inside the local or boost fields. The remaining 6 tumors also recurred locally; whether they were in-field or field margin recurrences was not to be discerned by the imaging available at the time. No out-field recurrences or spinal seeding were observed. For 8 of 17 locally irradiated patients with intracranial ependymomas, 5 local recurrences were recorded. In 9 of 17 patients receiving whole-brain or cranio-spinal irradiation, 6 local recurrences were found. Two of 8 spinal tumors recurred locally.
CONCLUSIONS: All tumors recurred within the former tumor bed. In the remaining cranio-spinal axis no recurrences or metastases were found. Similar results are reported from current literature. The value of large-field techniques (whole brain/spinal irradiation) is to be questioned. Modern methods like IORT or stereotactic radiotherapy might be able to deliver a higher tumor dose without increasing toxicity.