Late toxicity following craniospinal radiation for early-stage medulloblastoma.

Background: The purpose of this study is to review late toxicity following craniospinal radiation for early-stage medulloblastoma.

Material And Methods: Between 1963 and 2008, 53 children with stage M0 (n = 50) or M1 (n = 3) medulloblastoma were treated at our institution. The median age at diagnosis was 7.1 years (range 1.2-18.5). The median craniospinal irradiation (CSI) dose was 28.8 Gy (range 21.8-38.4). The median total dose, including boost, was 54 Gy (range 42.4-64.8 Gy). Since 1963, the CSI dose has been incrementally lowered and the high-risk boost volume reduced. Twenty-one patients (40%) received chemotherapy in their initial management, including 12 who received concurrent chemotherapy. Late sequelae were evaluated by analyzing medical records and conducting phone interviews with surviving patients and/or care-takers. Complications were graded using the NCI Common Terminology Criteria for Adverse Events, version 4.0.

Results: The median follow-up for all patients was 15.4 years (range 0.4-44.4) and for living patients it was 24 years (range 5.6-44.4). The overall survival, cause-specific survival, and progression-free survival rates at 10 years were 67%, 67%, and 71%, respectively. Sixteen patients (41% of patients who survived five years or more) developed grade 3 + toxicity; 15 of these 16 patients received a CSI dose > 23.4 Gy. The most common grade 3 + toxicities for long-term survivors are hearing impairment requiring intervention (20.5%) and cognitive impairment (18%) prohibiting independent living. Four patients developed secondary (non-skin) malignancies, including three meningiomas, one rhabdomyosarcoma, and one glioblastoma multiforme. Three patients (5.6%) died from treatment complications, including radionecrosis, severe cerebral edema, and fatal secondary malignancy.

Conclusion: Ongoing institutional and cooperative group efforts to minimize radiation exposure are justified given the high rate of serious toxicity observed in our long-term survivors. Follow-up through long-term multidisciplinary clinics is important and warranted for all patients exposed to radiotherapy in childhood.