A 15-year-old with a rare brain tumour is to undergo pioneering proton beam therapy at the UK’s first dedicated treatment centre.
Mason Kettley, from West Sussex, will receive the highly targeted therapy at the Christie NHS Foundation Trust in Manchester - home to the world's newest proton beam therapy centre.
What is proton beam therapy?
It is a highly targeted treatment that hits tumours much more precisely than conventional radiotherapy.
This makes it beneficial for patients with difficult-to-treat tumours in critical areas, such as in the brain or spinal cord, and for young people whose tissues are still developing.
It also helps shrink tumours and cuts the risk of side-effects.
Mason is one of the first patients to undergo proton beam therapy in the UK and the first to go public.
Until now, British patients needing the treatment had to travel to countries including the US.
He was diagnosed with an inoperable tumour in October after suffering headaches and failing to put on weight.
Doctors found the tumour was growing in a critical part of his brain but could not operate due to the risk of causing blindness and damage to vital brain tissue.
How does Proton beam therapy differ from Radiotherapy?
Science-loving Mason, who wants to work as a doctor specialising in tumours when he is older, said he did not initially have many symptoms.
He said: "I had some headaches and stomach pains and usual things, and got check-ups at the doctors."
Following a biopsy and an operation to insert a shunt, doctors referred Mason’s case to a national panel of experts.
They decided his tumour - known as a benign pilomyxoid astrocytoma - made him a suitable candidate for proton beam therapy.
Mason said he feels apprehensive about the treatment.
"It’s a bit nerve-wracking but this is a better choice than chemo because it’s more effective. Because of my age, (doctors) thought radiation would be a better choice.
"They said there's a chance of it spreading more tumours but I just hope it doesn't do that," he said.
"Their goal is to stabilise the tumour. It may shrink, but they are aiming to stabilise it. If it stabilises, then I can take medication to help me with the hormones and just get my life back on track," the teenager added.
Mason, who likes to spend his spare time on social media and watching films, is planning on going to McDonald’s once treatment has finished.
"I’m a fussy eater but I’ll be having large fries," he said.
Mason will have treatment Monday to Friday for almost six weeks - 28 sessions in total.
A specially made radiotherapy mask has been created to keep his head still during the therapy.
He said: "The short-term effects are that you may vomit and get a headache now and then, but in the long term the side effects are rare."
Two new proton beam therapy centres have been built at The Christie and University College London Hospital (UCLH) with £250 million of Government money.
Consultant clinical oncologist Gillian Whitfield, who is leading Mason’s care at The Christie, said: "With proton beam therapy, compared to conventional radiotherapy, there is less dose to surrounding normal tissues and less risk of permanent long-term effects of treatment.
"This is particularly important for children and teenagers with curable tumours, who will survive decades after treatment and are at much greater risk of serious long-term effects of treatment than adults.
"Mason’s tumour is a low grade (slow growing) tumour with a high chance of cure.
Professor Stephen Powis, medical director for the NHS in England said: "This is a hugely exciting development for the NHS and we are delighted that we are able to provide this life-changing treatment for patients like Mason."
Proton beam therapy hit the headlines in 2014 when the parents of Ashya King, who was due to undergo chemotherapy and radiotherapy at Southampton General Hospital, fled with him to Spain.
His father Brett has said Ashya is now cancer-free.