How proton beam therapy works?

Proton beam therapy has reportedly cured five-year-old Ashya King of brain cancer after his family removed him from hospital in Southampton and took him to Prague for the treatment.

So, what is proton beam therapy?

Q: How does proton beam therapy work?

A: Proton beam therapy is a type of radiotherapy that aims proton beams at cancers. Whereas conventional radiotherapy uses high energy beams of radiation to destroy cancerous cells, often damaging surrounding tissue, proton beam therapy aims radiation directly at the tumour. Because it is so highly targeted, it means it can avoid healthy tissue, particularly tissues and organs behind the tumour. While radiotherapy can lead to side effects such as nausea and can sometimes disrupt how some organs function, proton beam therapy has a lower risk of side-effects. This means it is effective for treating cancer that affects critical areas, such as brain cancer.

Q: Is it much better than conventional radiotherapy then?

A: Proton beam therapy is particularly useful for treating children whose bodies are still developing as it limits the collateral damage of radiation to other vital organs, such as the heart and liver in Ashya’s case. But although it may cause less damage to healthy tissue, it is still unclear whether it is as good at destroying cancerous tissue. As it is usually reserved for very rare types of cancer, comprehensive evidence about its effectiveness is also limited. Cancer Research UK estimates that only one in 100 people would be suitable for proton beam therapy.

There are also concerns that the long-term impact of the nascent procedure is not yet known. Although patients who have travelled abroad for treatment have responded well, like Ashya, these people would have been specifically chosen because of this.