What is the best option for my child: photon radiotherapy or proton beam therapy? 

Your child’s consultant and treating team will work closely with specialist radiotherapy teams to decide which type of radiotherapy is most appropriate for your child’s situation. They will consider your child’s age, the location of the tumour, how the cancer is behaving, and how to minimise side effects as much as possible. 

Both proton beam therapy (PBT) and photon radiotherapy can be effective treatments. The right option varies between children, and your child’s medical team will explain the reasoning behind their recommendation. 

What is the difference between proton beam therapy and photon radiotherapy? 

Radiotherapy treats cancer by damaging the DNA of cancer cells so they can no longer grow or divide. The difference between the two approaches lies in the type of radiation used and how it behaves inside the body. 

Photon radiotherapy 

Photon radiotherapy uses photons, which are the same type of energy used in X‑rays. This is the most widely used form of radiotherapy in the UK and has been a standard part of treatment for neuroblastoma for many years. 

Photons pass through the tumour and continue out the other side of the body. This means healthy tissue around and behind the tumour can receive some radiation. 

Proton beam therapy (PBT) 

Proton beam therapy uses protons, which are tiny charged particles found inside atoms. A machine called a cyclotron or synchrotron accelerates these particles and directs them precisely at the tumour. 

Protons behave differently to photons. They release most of their energy directly in the tumour and then stop, with very little radiation travelling beyond this point. This can help limit radiation to nearby healthy tissues. 

Are protons better than photons? 

Not always. Both treatments aim to control or eliminate the tumour, but their benefits depend on where the cancer is in the body and how it interacts with nearby organs and tissues. 

Current evidence tells us: 

• PBT is not shown to increase the chance of cure for neuroblastoma. 

• in some situations, it may reduce the risk of long‑term side effects by avoiding radiation to sensitive tissues. 

• for other children, photon radiotherapy may be the safer or more effective option, depending on tumour position, movement in the body, and how predictable the radiation dose will be. 

PBT is now available in the UK at specialist centres. It has known benefits in some childhood cancers, such as certain brain tumours. For neuroblastoma, it has been used in specialist centres abroad, but large‑scale studies comparing PBT and photon radiotherapy for neuroblastoma are still limited. 

Ongoing research, including UK‑based studies, aims to understand which children are most likely to benefit. 

Why might protons not be suitable for some children? 

Although protons can be very precise, their behaviour can be less predictable if the shape or position of tissues in the body changes. For example: 

• gas in the bowel 

• movement of organs as a child breathes 

• weight changes during treatment 

These small changes can affect how accurately the proton beam hits the tumour. In some cases, this may reduce the advantages of PBT, and photon radiotherapy may be safer or more reliable. 

Your child’s radiotherapy team will carry out detailed planning scans to understand these factors before recommending a treatment type. 

Evidence‑based information 

For families who would like to read more, CCLG provides a helpful overview of PBT and how it is being used in the UK: Could proton-beam therapy help more children.