Local control after craniospinal irradiation, intensity-modulated radiotherapy boost, and chemotherapy in childhood medulloblastoma

Background: The current study was conducted to determine whether the use of cochlear-sparing intensity-modulated radiotherapy (IMRT) boost results in excess local failures in children with medulloblastoma. Methods: Fifty children with a median age of 7.8 years underwent resection, craniospinal irradiation (CSI), IMRT posterior fossa (PF) and/or tumor bed (TB) boost, and cisplatin-based chemotherapy for medulloblastoma. For standard-risk patients, the CSI dose was 18 to 23.4 grays (Gy) and was followed either by an IMRT PF boost to 36 Gy and a TB boost of 54 to 55.8 Gy (n = 29) or by an IMRT TB boost to 55.8 Gy (n = 4). For high-risk patients, the CSI dose was 36 to 39.6 Gy followed by an IMRT PF boost to 54 to 55.8 Gy (n = 8), an IMRT PF boost to 45 Gy and a TB boost to 55.8 Gy (n = 2), or an IMRT TB boost to 55.8 Gy (n = 7). For the TB boost, a 2-cm margin around the surgical bed was treated in most patients. Results: The 5-year overall and progression-free survival rates (± standard deviation) were 72% ± 6.6% and 68.3% ± 6.8%, respectively, for all patients; 77.8% ± 7.4% and 75.1% ± 7.6%, respectively, for standard-risk patients; and 60.8% ± 12.8% and 55.4% ± 12.8%, respectively, for high-risk patients. The 5-year PF control rate was 90.5% ± 4.6%. TB failures occurred in 3 patients (including 2 patients who had distant failure), whereas an isolated non-TB PF failure occurred in 1 patient. Conclusions: The use of IMRT was associated with excellent local control and did not result in excess PF failures outside of the TB.