If you’ve heard about proton beam therapy in the news or elsewhere, you might be wondering what it actually is. We’ve all heard of surgery, chemotherapy and radiotherapy as treatments for cancer. But what is proton beam therapy? How does it work? And what makes it different from conventional radiotherapy?
Radiotherapy is one of the main types of cancer treatment in the UK. Around 40% of people who’ve had their cancer cured have had radiotherapy as part of their treatment. The treatment works by using high-energy radiation (x-rays) to treat cancer cells. Using a machine, the rays are aimed at the tumour. This damages the cancer cells, stopping them from dividing and destroying them. Although the rays are focussed on the tumour, they can also damage surrounding healthy tissue. This is what causes the side effects of radiotherapy. Unlike cancer cells, healthy cells can usually repair themselves so the damage to normal tissue is mainly temporary. Over the years, techniques and equipment have improved and it’s now possible to shape and aim radiotherapy more precisely. The idea is to deliver the highest possible dose to the tumour while doing as little harm as possible to surrounding healthy tissue.
Proton beam therapy is similar to radiotherapy, except it uses beams of protons rather than x-rays. The difference is that while x-rays release radiation during the course of their travels through the body, protons release almost all of their radiation at the spot they are aimed at. The beams also stop once they hit their target, rather than carrying on through the body to an exit, as happens with conventional radiotherapy. This means they cause less damage to healthy tissue.
The main advantage of proton beam therapy is that it can be very precisely aimed at a single tumour while causing less damage to surrounding healthy tissue. For this reason, it is used to treat cancers that are in one place (have not spread) and that are located in places where damaging surrounding tissue would be especially harmful. This includes some cancers affecting the back of the eye, the base of the skull or the spine. It’s also sometimes used to treat children with certain types of brain tumour, because damaging brain tissue in a child who is still developing can cause harmful long-term effects.
However, while proton beam therapy seems to cause fewer side effects than conventional radiotherapy, it’s not suitable for everyone and it’s also not currently easily accessible. In addition, because it’s only been used in a small number of cases and for specific types of cancer, it’s hard to know how effective it would be for most cancer patients.
At the moment there is one proton therapy centre in the UK, in Merseyside. The equipment they have can be used to treat rare types of eye cancer.
For other types of tumour, treatment is only available abroad. For patients in the UK, the NHS will fund this treatment if it is agreed that proton beam therapy is expected to be more beneficial than conventional radiotherapy. Currently, only about 1% of cases are judged to need proton beam therapy over conventional radiotherapy.
In the coming years, doctors will learn more about proton beam therapy, who it could benefit and the best way to use it. Access to the treatment in the UK will also be improved, with two proton beam therapy centres scheduled to open in 2018 in London and Manchester.
Alongside this, conventional radiotherapy continues to save thousands of lives across the board, and through research and trials it will continue to be improved to reduce side effects. Research is always underway to find new ways of making radiotherapy as effective as possible for individuals, and this has resulted in many different techniques for delivering radiotherapy.
For more information about cancer and cancer treatments, you can visit macmillan.org.uk/cancerinformation or call our support line on 0808 808 00 00.
Sources
* Cancer Research UK. Our research into radiotherapy. http://www.cancerresearchuk.org/science/research/who-and-what-we-fund/topic/radiotherapy/
(accessed 11 September 2014).
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