Our Head of Research and Information Dr Zoe Davison responds to some frequently asked questions about proton beam therapy.

What is proton beam therapy?

There have been a number of developments and advances in radiotherapy. Conventional radiotherapy uses x-ray beams to kill tumour cells, however, the doses that can be delivered are limited because the beams affect normal, healthy tissue in front of the tumour and behind it. Think of it as a spotlight, delivering the same dose of radiotherapy to the tumour and the normal tissue around it.

A newer version of x-ray radiotherapy is called intensity modulated radiotherapy. The x-ray beams can be shaped to target the tumour more accurately and are delivered from a number of different directions to limit the affects of the x-rays on normal tissue.

Proton beam therapy uses proton beams instead of x-ray beams; these beams cause very little damage to the tissue they pass through and are very good at killing the tissue at the end of their path. Scientists can work out exactly where the tumour is and ensure that the proton beams come to an end within it. This means that doctors can administer a higher dose of radiotherapy, while having little effect on normal healthy tissue.

Why are bone cancer patients seeking proton beam therapy abroad?

There are limited treatment options for primary bone cancer patients, especially for metastatic (cancer that has spread to other sites within the body) and relapsed patients. Conventional radiotherapy is not effective in many forms of primary bone cancer as the doses that can be delivered to ensure that normal tissues are not affected aren't high enough to kill the cancer cells. Many patients, at this stage, look to alternative treatment options such as proton beam therapy.

Does the NHS fund proton beam therapy abroad?

The NHS does fund proton beam therapy abroad for patients. This type of treatment has proven benefits in a number of cancers and it is patients with these types of cancers that tend to have this funded. The NHS has a 'UK proton panel' that assesses cases one by one to see which are eligible for NHS funding. Patients wishing to apply for this funding require a referral to this panel by a member of their clinical team.

When will proton beam therapy be available in the UK?

The UK was one of the first places to use proton beam therapy, however this is low energy proton therapy and is used successfully to treat eye cancer. High energy proton beam therapy requires sophisticated technology and equipment and needs a dedicated facility. The UK Government committed £250K to developing two proton beam therapy centres at the Chistie Hospital in Manchester and at UCLH in London. These are due to start treating patients in 2018 and 2020 respectively.

How effective is proton beam therapy for bone cancer specifically?

There have been very few studies looking at the effectiveness of proton beam therapy in bone cancer patients specifically. One study in America looked at its effectiveness in osteosarcomas of the spine, pelvis and skull base, and showed that it was effective in some patients.

Once the UK is treating patients, more thorough studies will be needed to fully assess the effectiveness of this treatment in primary bone cancer.

To support the development of improved radiotherapy for bone cancer patients more widely, the Bone Cancer Research Trust has funded a significant piece of research, firstly assessing the use of intensity modulated radiotherapy and secondly, preparing processes and protocols in preparation for proton beam therapy being established in the UK.

For more information about proton beam therapy, you can visit the NHS website.