Sally Roberts has exclusively told ITV Daybreak that she is concerned that radiotherapy treatment could be damaging to her son Neon, by affecting his DNA.
She said there are "so many" other treatments that her son could be having instead.
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Under the new rule adults over the age of 18 automatically become donors after their death, unless they opt out beforehand.
Doctors have recommend Peter Sutcliffe be moved to high security prison, but the final decision will be taken by the justice secretary.
Last minute suspension of strike action has meant thousands of cancelled procedures will still not go ahead.