1 Department of Paediatric Oncology, Great North Children's Hospital, Queen Victoria Road, Newcastle upon Tyne, NE1 4LP, UK. vickyanne.carruthers@nhs.net.
2 Department of Paediatric Oncology, Great North Children's Hospital, Queen Victoria Road, Newcastle upon Tyne, NE1 4LP, UK.
3 Wolfson Childhood Cancer Research Centre, Newcastle University Centre for Cancer, Newcastle upon Tyne, UK.
4 Department of Neurosurgery, Royal Victoria Infirmary, Newcastle upon Tyne, UK.
5 Sir James Spence Institute for Child Health, Royal Victoria Infirmary, Newcastle upon Tyne, UK.