A British High Court judge has ruled a seven-year-old boy will receive radiotherapy for a brain tumour against the wishes of his mother - whose judgment, the judge says, has "gone awry".
Mr Justice Bodey dismissed Sally Roberts' attempt to prevent radiotherapy treatment for her son, Neon - and expressed concern over her decision-making regarding the child's welfare.
Roberts, who had earlier failed in a similar legal bid to prevent surgeons performing a follow-up operation on the boy, said she feared radiotherapy would cause long-term harm.
Bodey, who had been told by doctors Neon could die within months without radiotherapy treatment, said he sympathised with the "nightmare" confronting Roberts. But he said he was worried she had not grasped the seriousness of Neon's situation.
"The mother has been through a terrible time. This sort of thing is every parent's nightmare and I have sympathy for her," said the judge, following a hearing in the Family Division of the High Court in London.
"But I am worried that her judgment has gone awry on the question of the seriousness of the threat Neon faces."
He said the operation Roberts had opposed was lifesaving and added: "I have become concerned about the mother's attitude to Neon's welfare generally."
The judge ruled that radiotherapy sessions could start and said Neon should live with his father, Ben - who is separated from Roberts - for the duration of his treatment.
He said doctors would need only Ben Roberts' consent when making future decisions about Neon's cancer treatment.
He said it was important doctors were not hampered by a "stalemate" if parents took differing views.
Sally Roberts, 37, a New Zealander who lives in Brighton, said after the hearing she was "not allowed" to comment.
Neon's father , who lives in London and had consented to radiotherapy, was said to be "relieved". He was reportedly at Neon's hospital bedside when the judge made his decision.