Media playback is unsupported on your device Media caption Sally Roberts: "He's very good in himself"

A judge has postponed a decision on whether a mother should be allowed to prevent her son from receiving radiotherapy for brain cancer.

Sally Roberts, 37, has been told seven-year-old Neon could die if he did not receive the treatment.

She said she feared the treatment could do long-term harm.

At the High Court in London, Mr Justice Bodey said he would rule at a hearing beginning on 18 December - unless agreement could be reached beforehand.

During the Saturday morning hearing, he said that although he had intended to rule on the matter, developments had "changed the medical landscape".

After the hearing at the Family Division, New Zealand-born Ms Roberts said she "can't add to what the judge said".

She added that, health-wise, her son was "very good in himself". Neon's father, Ben, said he would not comment.

'Lower IQ'

Analysis - radiotherapy for brain tumours Radiotherapy can cause a number of short-term side effects, including hair loss on the area of the head being treated, sickness and tiredness. Sometimes it can make symptoms worse before they get better because it causes swelling, which increases pressure in the head. This can be treated with steroids. Some patients go on to develop new symptoms weeks to months after treatment, which include poor appetite, sleepiness, lack of energy and a worsening of old symptoms. This may be due to damage caused to nerve tissue or healthy brain cells, and the symptoms usually disappear over time. A minority of patients develop long-term, enduring side effects, which are caused by more permanent changes in the brain tissue. These can include problems thinking clearly, poor memory, confusion, and personality changes. These symptoms are less common than they once were because modern radiotherapy can be delivered very precisely to diseased areas. They tend to be more common in children, whose nervous systems are still developing. It is important to stress that for most the benefits of radiotherapy far outweigh the risks.

Sally Roberts went into hiding with her son on Wednesday, sparking a nationwide search before both were found unharmed.

The boy was operated on last year and a tumour was removed successfully.

The judge is being asked to decide whether it is in Neon's best interests to undergo treatment.

Doctors have said it was "clearly" in Neon's best interests to undergo radiotherapy and chemotherapy, arguing the treatment was standard procedure and offered Neon the best chance.

However, Ms Roberts said she only wanted her son to have chemotherapy, as she feared radiotherapy would result in long-term brain damage, reducing his IQ and also possibly making him infertile.

A lawyer representing the health authorities who are treating him told the court the "alternative is death".

A barrister outlined Ms Roberts's position in written arguments at the start of the hearing.

"Much sympathy it is hoped will be felt for her overall position," Robin Tolson QC told the court.

Image caption Doctors and Neon Roberts' mother do not agree on what his next treatment should be

"The mother's position in this litigation... is principled, reasonable and in the best interests of Neon."

Ms Roberts told the court on Friday that she was not a "bonkers mother" and her barrister described her position as "principled".

Ms Roberts apologised to the court and said she only wanted the best for her son.

The judge has described Neon's illness as the "stuff of every parent's nightmare" and has said he will balance what radiotherapy treatment would achieve against the "downsides".