The technique of craniospinal irradiation in the management of intracranial ependymomas.

Purpose: To present a new technique of craniospinal irradiation as a postoperative prophylactic treatment in patients with intracranial ependymomas being at risk for relapse.

Patients And Methods: In the last 3 years, 9 pediatric patients under 15 years of age with grade 2-4 ependymomas located infratentorially received postoperative craniospinal axis radiotherapy by a new technique developed in our department. This technique was based on a proper usage of the asymmetric jaws of the linear accelerator. In whole brain and cervical spine irradiation (with the caudal border at C3-C4 level), two opposite lateral fields were chosen with shielding blocks of the eye bulbs and the face part of the scull. The spinal cord was irradiated from C3 to S2-4 with two direct radiation fields using asymmetric jaws as well. Doses of 35 Gy to the whole craniospinal axis and 54 Gy to the tumor bed were delivered. In cases of residual tumor doses were increased up to 58-60 Gy.

Results: Radiotherapy was well tolerated and dose reduction was not needed in any case. Skin reactions were mild in all patients. The gastrointestinal and hematological toxicity were also mild to moderate (World Health Organization - WHO grade 1-2). Four patients also received postirradiation chemotherapy because of large tumor size and unfavorable histology. Six patients entered clinical and imaging complete remission (CR) for a median of 22 months (range 14-30 months). The evaluation of the effectiveness of the method was limited by the short follow-up interval.

Conclusion: The proposed new technique of craniospinal irradiation in the postoperative management of highrisk ependymomas is advantageous in terms of side effects and could be recommended for wide usage.