Woman whose son had to go to America for treatment asks minister to invest in same technology

When, in February 2007, Rosalie Barnes was told that her son Alex, then aged just three, had an advanced brain tumour, doctors in her native Leicestershire were forced to concede that his prospects were limited at best.

The most optimistic medical assessments put his likelihood of surviving the tumour at between 25 and 35 per cent. Other, more candid, doctors put it much lower. Even the most sophisticated treatments offered by the NHS, Mrs Barnes was told, could only mitigate the tumour's growth.

Her trauma was accentuated after an initial operation in September 2007 appeared to remove the cancer completely, only for it to return with renewed vigour months later. So the trip that she and her son made to London yesterday could never have been imagined two years ago. Alex has fully recovered, and is now as sprightly as the average five-year-old.

Taking the train from their home town of Fleckney to London's Euston station, mother and son headed for the Department of Health. They met minister Ann Keen to spread the gospel of proton therapy – a technology which saved Alex's life, but which remains beyond the budget of our health service.

Last September the schoolboy flew to Florida for the advanced form of cancer treatment. It involves the insertion of tiny metal balls into the patient's head to direct lasers to cancerous tissue, and is thought to be particularly effective at combating tumours in children.

However, the machines required for proton therapy cost £70m each. The expense has been used to justify their absence from British hospitals – which is precisely why Mrs Barnes and Alex went to meet the minister.

"I have the full backing of so many doctors both in the UK and in America, all of whom recognise that the radiotherapy we've got here is not suitable for children under five," Mrs Barnes said yesterday.

The 44 year-old, who works as a fashion designer, is lobbying the Government to build two proton therapy centres, one in the north of England and one in the south, each costing around £100m.

"I came across proton therapy quite by accident. When I found out about the tumour I looked it up on Google images, wanting to know what this horrible thing in my son's head looked like. Then I saw a link about proton therapy and got very excited. Initially we wanted to go to Paris or Zurich, where the treatment is cheaper. But I rang up my parents, who live in Florida, and they said a new machine had been installed just down the road from them."

Alex spent three months in America receiving treatment. During that time his teachers at Stoneygate School in Great Glen, Leicestershire, sent him occasional pieces of homework, while his mother kept up his spirits by taking him on day trips to Disney World, Florida Zoo, and the beach.

Alex's operation, which cost £100,000, was half-funded by donations from the Leicestershire public, after a campaign by the Leicester Mercury newspaper.

For now, the NHS is prepared to help patients in need of proton therapy find it overseas. A Department of Health spokeswoman said: "An expert advisory group has been formed to advise the department and establish a framework for the development of proton therapy services in England. In the meantime, there is funding available for a number of cancer patients to be referred overseas for high energy proton treatment."

Alex is back at school and doing well. "The thing about proton therapy," said Mrs Barnes, "is that it is much more accurate and doesn't do any of the peripheral damage that radiotherapy causes." She added: "Alex is getting on really, really well. His hair has grown back and he's just a normal kid again. It's fantastic!"