The Government decided on Friday that the unit will move to Evelina Children’s Hospital in central London from 2026.
Jenny Houghton’s son was successfully treated at the Marsden.
She says Health Secretary, Victoria Atkins, needs to step in.
NHS England says the Evelina was chosen following a rigorous process.
This included a public consultation and an options-appraisal process involving clinical advisers, parents, charities, nurses, and researchers.