Late response to radiochemotherapy in pediatric glioblastoma: report on two patients treated according to HIT-GBM protocols.

High-grade gliomas in children are rare and the best treatment is undetermined. The German language group study HIT-GBM compares various induction protocols for subsequent patient cohorts. Currently, cisplatinum, etoposide, ifosfamide, and vincristine are given simultaneously with extended-field radiotherapy. Imaging is done 3 weeks after to define treatment response, followed by 6-weekly controls during consolidation with lomustine, vincristine, and prednisone. The authors report on 2 patients with incompletely resected glioblastoma multiforme in which response was lacking 3 weeks after radiochemotherapy but became evident 12 weeks later. This suggests that later time points are required to assess induction protocol response.