Families who have a child living with cancer fear going on a three hour journey for treatment if the NHS pushes ahead with plans to move services.
The hospital doesn't have an intensive care unit which the NHS says is necessary to prevent risks to children being driven by ambulance to urgent treatment, although health bosses insist current procedures are safe.
Under the proposals, services would move either St George's in Tooting eight miles away or to the Evelina London Children's Hospital thirteen miles away in Lambeth.
Radiotherapy would then be offered at University College Hospital twenty miles away in Euston, north of the River Thames.
Kat Litchen's son Teddy is among the hundreds to be receiving treatment at The Royal Marsden.
The four year old, from Hassocks in West Sussex, has been under the care of the hospital for more than a year after being diagnosed with a rare and aggressive form of the disease.
If the changes go-ahead, a 50 minute journey would take three times as long.
Kat said she was in disbelief hearing about the proposals, "I couldn't believe it at first. It seemed completely ridiculous that they would be closing a children's cancer centre, which was only 12 years old and was on the site of one of the best research facilities in the world.
"There's a lot of worry. There's a lot of concern about the standard of care, about the staff, and whether we'll have that continuity of care and around clinical trials.
"Instead of traveling 50 minutes to the Marsden, which we currently do, we would be spending two and a half to 3 hours each way.
"The report says that many people would have a shorter travel time, but that's based on public transport, which isn't possible for children receiving cancer treatment in many cases. When they receive chemotherapy, their immune system is too suppressed for that to be a safe option for them."
A petition against the changes has been signed by 6,500 people but the NHS insist the proposals must be implemented and that high-quality care will remain.
The plans would come into place in 2026 with a consultation ongoing until midnight on December 18th.
Dr Chris Streather, Medical Director, NHS England (London) said ,
"The Royal Marsden has an impressive track record of delivering high quality care for children but the pace of innovation in children’s cancer treatment means that, to be fit for the future, the centre must move to be with intensive care.
"Like other major centres worldwide, the new centre will then be ready to offer innovative life-saving new treatments that wouldn’t be possible under the current arrangements, as they have a greater risk of complications and needing intensive care expertise.
"We have two strong options for the future location of the Centre and want to get feedback from children, families and staff throughout this consultation."
Kat Lichtens explains that the treatment would still require patients visiting multiple sites
Kent-based The Chartwell Charities currently provides patient transport for families to and from The Royal Marsden.
If the services do move then the transportation would not be financially sustainable for the charity and would need to stop.
"The move is going to be devastating. If all those children that are treated in Marsden now have to be treated at Evelina or in Tooting we wouldn't be able to offer that service any longer.
"So that would be many more patients put in difficulty getting to and from their appointments.
"For the families that use the Royal Marsden, I think their minds really put at ease because they know they're receiving first class world class service.
"They also have access to the Institute of Cancer Research, which is based in the Royal Marsden. So they get opportunities to trial, new research, new clinical trials, something that might be lost if those services are all transferred to London Hospital."
Professor Nicholas van As, Medical Director for The Royal Marsden NHS Foundation Trust, said,
"The current service at The Royal Marsden is assessed as high-quality and safe, and a third of children treated in the hospital are able to access clinical trials through our world leading Oak Paediatric and Adolescent Oncology Drug Development Unit.
"It’s important that the benefits currently available to children at The Royal Marsden are retained in the future."
Cancer care for patients aged 16 and above will continue to be delivered at The Royal Marsden,
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