Proton Beam Therapy
Proton beam therapy (PBT) is regularly in the news, largely due to number of children travelling to the United States for this specialised form of radiotherapy. It has, at times, been controversial, particularly in the case of Ashya King, a five-year-old boy with a brain tumour. His parents sparked an international manhunt when they took him out of Southampton hospital (where he was being offered traditional radiotherapy) in a bid to get PBT for him abroad.
But what exactly is PBT and why has it been hitting the headlines so often in the last couple of years?
Traditional external beam radiotherapy uses high energy X-rays to target and kill cancer cells whereas PBT uses high energy beams of particles called protons. Protons offer a number of advantages over X-rays. One of the main benefits of a proton beam is that it does not pass all the way through the patient’s body. This means the beam can be precisely delivered into the tumour, stopping before it travels any further. This highly accurate delivery mechanism can greatly reduce the risk of side effects, as healthy tissue around and behind the tumour can be avoided with far greater accuracy.
The precision of the treatment means it is particularly valuable in treating cancers in areas of the body which are particularly delicate, such as the brain, and in children’s cancers. As children’s bodies are still growing, the more that can be done to reduce side effects may help to prevent long-term complications in adulthood.
Ashya King eventually received PBT at the Proton Therapy Centre in Prague. The centre’s medical director, Dr Jiri Kubes, said at the time: “Proton therapy maximises curability while significantly minimising the risk of possible side-effects, ultimately preserving patients’ quality of life.”
Cases such as Ashya King’s have led many people to believe that PBT is the best radiotherapy treatment for cancer, offering the best chance of survival. However, while PBT offers benefits in some situations, it is not as clear cut as the impression given by many news stories.
Dr Adrian Crellin, NHS England’s clinical lead on proton beam therapy said: “Since it delivers a lower dose of radiation to surrounding tissues, proton beam therapy’s main advantage is in reducing side-effects, rather than improving survival or cure….It’s critical to stress that for most patients right now, there’s no strong evidence that proton beam radiotherapy is ‘better’ at curing cancer, or improving a patient’s chances of survival, than conventional X-ray radiotherapy”. Dr Crellin says much more research into PBT is needed.
One piece of research, published by a team of researchers from Massachusetts General Hospital in the US, found PBT caused fewer side-effects in children than conventional radiotherapy. The researchers studied 59 patients aged between three and 21 and found that after five years, the children’s survival rate was similar to that of patients treated with conventional radiotherapy, but there were fewer side-effects to the heart and lungs.
Dr Kubes from the Proton Therapy Centre in Prague explains: “Overall, the main advantage of proton therapy is the preservation of quality of life.”
So, what is the situation in the UK? Since 2008, patients have been able to access PBT abroad through the NHS Proton Overseas Programme. To get funding – which pays for travel and accommodation as well as the treatment – patients have to meet special NHS criteria after being referred to a panel of clinical experts by their specialist. So far, more than 800 patients have been approved through the programme, 70% of whom have been children. The average cost is around £90,000 per person. If patients fail to obtain NHS finding, there is the option to pay for treatment themselves, with many now turning to crowdfunding and public donations. It is usually the patients who don’t meet the NHS criteria and are denied funding who hit the headlines.
High-energy PBT facilities for the UK are currently being constructed and PBT will be available to treat eligible cancer patients at the Christie Hospital in Manchester in 2018, and at University College London Hospitals in 2019. Once these facilities are open, it will mean eligible UK patients will no longer have to travel abroad for treatment.
Professor Pat Price, Chair of Action Radiotherapy, said: “It is very good news that the NHS will be opening its own PBT facilities in the next few years. This will remove the burden of travelling abroad for families already facing a stressful time. However, it is important to remember that the treatment isn’t suitable for everyone. Only one per cent of people who currently receive radiotherapy will be suitable for PBT. There are many other forms of modern radiotherapy, such as SBRT and IMRT, which can be extremely effective too. Action Radiotherapy wants all patients to receive the best type of radiotherapy for their particular cancer.”
You can watch a video explaining how Proton Beam Therapy works and what impact the new PBT centres in the UK will have on the service that the NHS provides.