About proton beam therapy

If a young person or child has a certain type of cancer, tyour consultant may recommend they travel abroad to have a specialised form of radiotherapy called high-energy proton beam therapy.

What is proton beam therapy?
How does proton beam therapy work?
How is proton beam therapy given?
What are the side effects?
How can I find out more about proton beam therapy?

What is proton beam therapy?

Proton beam therapy is a type of radiotherapy. Conventional radiotherapy usually uses high-energy x-rays (also called photons) to destroy cancer cells. Proton beam therapy uses small parts of atoms called protons instead.

There is no difference in terms of the damage the two types of radiotherapy cause to cancer cells, but they deliver the radiation dose slightly differently. The protons release their energy at the site of the tumour and can target it more precisely than x-rays can.

High-energy proton beam therapy isn’t currently available in the UK. However, the NHS will pay for carefully selected patients to have proton therapy at hospitals in other countries, usually Switzerland and the USA, if this is felt to be the best treatment for them. Most children who need proton beam therapy are treated in the USA.

How does proton beam therapy work?

Like other forms of radiotherapy, the aim of proton beam therapy is to destroy the DNA in cancer cells. DNA is the instruction code that tells a cell what kind of cell it is and what job it has to do. Destroying it kills the cancer cells and shrinks the tumour.

With proton therapy, the protons deposit the radiation dose at the site of the tumour, and this reduces damage to surrounding healthy tissue. X-rays, on the other hand, continue to deposit radiation in healthy tissue beyond the tumour as they exit the body, potentially causing side effects. Because of this, doctors may recommend proton therapy if a young person or child has a tumour that is close to delicate parts of the body, such as the brain or spinal cord.

In children, proton beam therapy may be suggested for:

  • Certain brain tumours, including craniopharyngiomas and low-grade gliomas
  • Certain sarcomas, including parameningeal rhabdomyosarcomas, Ewings sarcoma and pelvic sarcomas
  • Retinoblastoma
  • Pineal parenchymal tumours.

In young adults, proton therapy may be used to treat:

  • Base of skull and spinal chordoma
  • Base of skull chondrosarcoma
  • Spinal and paraspinal bone and soft tissue sarcoma (non Ewings).

How is proton beam therapy given?

Young people or children having proton beam therapy are treated as outpatients. Treatmentsare usually given daily from Monday to Friday with weekends off. The treatment course usually lasts about seven to eight weeks in total.

Because proton beam therapy is so carefully targeted, it is very important that people having it stay still during the treatment. If you are having proton beam therapy on your head or neck, you may have a special mask made for you that keeps your head still. For younger children, who are more likely to move around,staff at the therapy centre may use a special beanbag shaped to their body or straps to help them stay still. Younger children may also be given an anaesthetic to make them sleep.

Proton beam therapy is painless and treatments usually last about one hour to one and a half hours in total. If your child needs an anaesthetic, you may need to spend about three hours to three and a half hours at the treatment centre to allow them time to recover.

What are the side effects?

Although research is limited, proton beam therapy seems to have fewer side effects than standard radiotherapy. This is because it targets cancer cells more accurately so that less healthy tissue gets harmed.

The side effects of proton beam therapy vary according to which part of the body is being treated. They also depend on:

  • The dose and duration of treatment
  • Any other existing conditions
  • Any previous surgical procedures
  • Whether or not you (or your child) are also having chemotherapy.

Side effects can happen during the therapy, immediately afterwards or months to years later. Side effects during treatment can include:

  • Sore skin
  • Hair loss (if the head is being treated)
  • Sore mouth (if the face is being treated)
  • Diarrhoea, nausea and vomiting (if the pelvis or abdomen is being treated)
  • General tiredness

Your consultant in the UK and the doctors at the proton therapy centre abroad can both give you more detailed information about possible side effects before treatment starts. Doctors at the therapy centre will closely monitor any side effects during treatment and will be available to answer any concerns you may have.

How can I find out more about proton beam therapy?

You’ll find more information about proton beam therapy from the NHS Specialised Services website.

June 2012, next planned review March 2013