Low Dose Versus Usual Dose Dexamethasone for Symptom Control in Children Undergoing Cranial or Craniospinal Radiation

Inclusion Criteria for Enrolment: * Children between 2-18 years of age. * Children who underwent resection of a brain tumour with ≤ 1.5 cm2 residual tumour after surgical resection. * Children regardless of extent of leptomeningeal or spinal metastasis (M1-3) are eligible. * Children who undergo focal or whole brain (± spinal) radiation as part of their brain tumour treatment. * Children treated at one of the 16 tertiary care centers in Canada (CPBTC). * Patients on any anticonvulsive treatment are eligible. * Patients on concomitant chemotherapy while undergoing radiation are eligible. * Patients must be ≥ 24 hours steroid-free prior to starting radiation. * Parents/legal guardians have to have signed and dated an informed consent to allow study enrolment of their child. (As per institutional guidelines, patients over a certain age may have signed their own informed consent form.) * Patients \> 8 years of age should assent to study participation. * Patients less than 10 years of age should have a Lansky Score of \>/= 50. * Patients 10 years of age or older should have a Karnofsky Score of \>/= 50. If ECOG performance scale is used, patient should have a score of 0, 1 or 2. Exclusion Criteria for Enrolment: * Children with residual brain tumour lesion \> 1.5 cm2 after surgical resection. * Children on steroids (dexamethasone) that will not be stopped ≥ 24 hours prior to start of radiation therapy. Inclusion Criteria for Randomization to a Dexamethasone treatment group: * Patients must have been enrolled on the Dexamethasone study prior to the start of radiation therapy. * Children who develop either symptoms of vomiting (defined as either retching or vomiting ≥ once per day) or headache (≥ 2 points increase in severity of the most intense headache/day) while undergoing irradiation. * Patients who are currently undergoing focal or whole brain (± spinal) radiation. Exclusion Criteria for Randomization to a Dexamethasone treatment group: * Patients who were not enrolled on Dexamethasone study prior to start of radiation therapy.