This is an international prospective randomised trial, which will compare two radiotherapy regimens in children and adolescents (aged 4 or 5 years to 21 years inclusive) with carefully staged 'standard risk' medulloblastoma.

Patients eligible for the study will be those with non-metastatic medulloblastoma (by imaging and CSF cytology) at diagnosis. Patients randomised to the standard arm will receive conventionally fractionated (once a day) radiotherapy with a dose of 54 Gy to the posterior fossa and 23.4 Gy to the craniospinal axis. The experimental arm will be hyperfractionated (twice a day) radiotherapy (1 Gy b.d.) with a dose of 60 Gy to the posterior fossa with an additional 8 Gy to the tumour bed and 36 Gy to the craniospinal axis. Both groups will receive identical chemotherapy consisting of eight weekly doses of Vincristine given with radiotherapy and 8 courses of CCNU, cisplatin and vincristine following radiotherapy.

Inclusion Criteria:

• Age at diagnosis at least 4 years or 5 years (according to the policy of the National Brain Tumour Group) and less than 22 years.
• Histologically proven medulloblastoma, including the following variants(WHO classification - 2000): classic medulloblastoma, nodular / desmoplastic medulloblastoma, melanotic medulloblastoma, medullomyoblastoma No CNS metastasis on MRI - supratentorial, arachnoid of the posterior fossa or spine.
• No clinical evidence of extra-CNS metastasis
• No tumour cells on the cytospin of lumbar CSF. Central Review of CSF cytology is recommended but not mandatory. It will be left to national policy.
• Radiotherapy to start no more than 40 days after surgery.
• Ability to receive twice daily radiotherapy.
• Vital functions within normal range for their age group.
• CTC grades < 2 for liver, renal, haematological and audiological function.
• No medical contraindication to radiotherapy or chemotherapy.
• Written informed consent (and patient assent where appropriate) according to the laws of each participating country. Written informed consent should also be sought for biological studies.
• National and local ethical committee approval according to the laws of each participating country (to include approval for biological studies).

Exclusion Criteria:

• One of the inclusion criteria is lacking.
• Brainstem or supratentorial primitive neuroectodermal tumour.
• Atypical teratoid rhabdoid tumour.
• Medulloepithelioma.
• Ependymoblastoma.
• Large cell médulloblastoma.
• Metastatic medulloblastoma (on CNS MRI and/or positive cytospin of postoperative lumbar CSF).
• Patient previously treated for a brain tumour or any type of malignant disease.
• Patients who are pregnant.
• Females who are sexually active and not taking reliable contraception.
• Known predisposition to medulloblastoma e.g. Gorlin's syndrome.

Sponsor will share de-identified data sets. Documents generated under the project will be disseminated in accordance with Institut Curie policies.

Data requests can be submitted starting 9 months after last article publication and will be made accessible for up to 12 months.

Access to trial individual participant data can be requested by qualified researchers engaging in independent scientific research, and will be provided following review and approval of a research proposal and Statistical Analysis Plan (SAP) and execution of a data sharing agreement (DSA).