Proton beam therapy

Proton beam therapy is a type of external beam radiotherapy.

It is used to treat children and young people, because their normal cells are still developing. It may be used for cancers in adults if:

  • they are close to important structures, such as the spine
  • there is a high risk of long-term side effects.

Proton beam therapy uses protons rather than x-rays to destroy cancer cells. It may cause fewer, or milder, effects than standard radiotherapy, because:

  • the beam is likely to cause less damage to normal cells
  • the beam stops when it reaches the cancer, so normal cells behind the cancer are not damaged.

Proton beam therapy may be given on its own, or with other treatments. Treatment is carefully planned. You usually have it daily, Monday to Friday, for around 8 weeks.

Side effects depend on the part of the body being treated, but may include tiredness and skin reactions.

Proton beam therapy has been available in the UK from late 2018. Your team will give you more information if it is suitable for you.

What is proton beam therapy?

Proton beam therapy is a type of external beam radiotherapy.

Proton beam therapy is only suitable for a small number of people. It is used to help reduce the risk of long-term side effects that can sometimes develop after standard radiotherapy. It can also be used to treat cancers that are close to important structures in the body (see below for more information). These cancers may be difficult to treat with standard radiotherapy or surgery.

Proton beam therapy is given using specialised equipment that is not available in all UK hospitals. You may be referred to a specialist hospital if your cancer doctor thinks it is a suitable treatment for you.

Radiotherapy explained

Consultant Clinical Oncologist Vincent Khoo describes external beam radiotherapy, how it works, and what it involves.

Information about our videos

Radiotherapy explained

Consultant Clinical Oncologist Vincent Khoo describes external beam radiotherapy, how it works, and what it involves.

Information about our videos


How proton beam therapy works

Radiotherapy uses high-energy rays to treat cancer. It destroys cancer cells in the area where the treatment is given. The aim is to:

  • stop the cancer cells growing
  • shrink the cancer or completely destroy it.

Standard radiotherapy uses high-energy x-rays. The radiotherapy is carefully aimed at the cancer, but it passes through some normal cells surrounding the cancer. Some of the normal cells are damaged by the radiotherapy, which may cause side effects. These depend on the area being treated, but may include a skin reaction, feeling sick and inflammation. Most side effects are temporary.

Proton beam therapy uses protons instead of x-rays. Protons are parts of atoms. The protons can be sped up by a machine called a particle accelerator or cyclotron. The protons are then shaped into a beam that is targeted at the cancer.

The proton beam passes through normal cells until it reaches the cancer. When it reaches the cancer, the proton beam slows down and stops. The protons then release all their energy, which damages the cancer cells.

Proton beam therapy and standard radiotherapy
Proton beam therapy and standard radiotherapy

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Proton beam therapy may cause fewer, or milder, side effects than standard radiotherapy. This is because:

  • the proton beam is likely to cause less damage to normal cells as it passes through them
  • the beam stops when it reaches the cancer, which means it does not damage any normal cells behind the cancer – this is different to a standard radiotherapy beam which continues through the cancer.

Proton beam therapy can be used to give high doses of radiation to the cancer, with less damage to nearby normal cells.


When proton beam therapy is used

Proton beam therapy is not suitable for everyone.

It is used to treat children, teenagers and young adults, because their normal cells are still developing. It can be better for these groups than standard radiotherapy, because it:

  • reduces the risk of damage to developing cells
  • helps prevent long-term problems.

It can also be used to treat adults with cancers:

  • that can be difficult to treat because of where they are in the body
  • that are in a position where the side effects of standard radiotherapy would cause serious problems
  • where there is a high risk of late side effects from standard treatments
  • that do not respond well to standard radiotherapy and would need a very high dose of treatment to be effective
  • that have come back after being treated with standard radiotherapy.

Proton beam therapy may be given on its own or in combination with other treatments. For example, it may be given with surgery, standard radiotherapy and chemotherapy.

Proton beam therapy may cause fewer side effects, but it is still quite a new treatment in the UK. Research is needed to find out more about its long-term benefits and side effects, and to compare it with standard treatments.

It is also important to remember that when treating most types of cancer, standard radiotherapy is a very effective and safe treatment. Standard radiotherapy can cause side effects, but they usually get better when the treatment has finished. Long-term side effects are uncommon.

Your healthcare team will give you more information if proton beam therapy is suitable for you. It may be given as part of a research trial (clinical trial).

Children, teenagers and young adults

Proton beam therapy can help reduce the risk of long-term effects on normal cells, such as the brain or bones.

It is mainly used to treat some types of brain tumour. But it can also be used to treat:

  • types of soft tissue sarcoma, such as rhabdomyosarcoma and fibrosarcoma
  • types of primary bone cancer, such Ewing’s sarcoma
  • cancers in the pelvic area
  • cancers in the head and neck area.

Adults

Proton beam therapy can also be used to treat cancer in adults. At the moment, it is mainly used as part of a research trial to treat cancers that are close to important structures. This includes cancers affecting the:

  • base of the skull
  • spine.

Low-dose proton beam therapy is also commonly used to treat cancers affecting the eye, such as ocular melanoma. Proton beam therapy may sometimes be used to treat other cancers. It may also be used to treat areas of the body that have previously been treated with standard radiotherapy.

Proton therapy was better for me than chemotherapy – I was not that sick. Normal radiation would have destroyed my bowel and ovaries. I felt lucky to be eligible for the treatment.

Ruth


Planning your proton beam therapy

Before you start your treatment, it needs to be planned. This is to make sure the proton beam therapy:

  • is aimed precisely at the cancer
  • causes the least possible damage to nearby normal cells.

Proton beam therapy is planned for each person by a clinical oncologist and a specialist proton beam therapy team.

It is important to tell the hospital staff about any medications you are taking and if you have any allergies. If you take painkillers, they may advise you to take them before your planning and treatment, so you are comfortable.

Masks and moulds

You may need to have a mask or mould made before planning starts. This is to help you stay still and in the correct position during your proton beam therapy.

Masks keep your head and neck area still. They are often used for planning and treatment to the brain, head and neck or upper chest area. Sometimes they are called thermoplastic shells or immobilisation devices.

A radiotherapy mask
A radiotherapy mask

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Moulds are used to keep a leg, arm or other body part still during planning and treatment. Your doctors will tell you more about this if you need one.

We have more detailed information about how radiotherapy masks and moulds are made.

Imaging and planning

You start planning by having a specialised CT scan. You may also have an MRI scan.

These scans take lots of pictures from different angles, to build up a 3D picture of the area to be treated. A computer uses the information from the scans to make an individual plan for your treatment. This makes sure the proton beam therapy is precisely targeted at the cancer. which helps reduce the risk of side effects.

Skin markings

You may have markings made on your skin. This helps the person who gives the proton beam therapy (radiographer) position you accurately for treatment.

Usually, tiny permanent markings are made in the same way as a tattoo. The marks are the size of a pinpoint and they are only made with your permission. It can be a little uncomfortable while they are being made, but it makes sure the treatment is directed accurately. If you have a mould or mask, the marks may be made on this.

It can take 2 to 3 weeks to make a treatment plan. When it is ready, you can start treatment.

Pacemakers and implantable cardiac devices

If you have a pacemaker or an implantable cardiac device (ICD), you must tell your cancer doctor when you discuss treatment. You should also tell your radiographer, either before or during your first planning appointment. Proton beam therapy can affect these devices, so your treatment needs to be planned to allow for them. Your cardiology team should also check the pacemaker or ICD.


Having proton beam therapy

Treatment sessions

You usually have proton beam therapy as an outpatient. The number of treatments you have will depend on the type of cancer you have. You usually have 1 session of treatment a day from Monday to Friday, with a rest at the weekends. The treatment normally lasts for up to 8 weeks. This is called a course of treatment. Your cancer doctor, specialist nurse or radiographer will explain the treatment plan to you.

Each appointment usually takes about 30 to 45 minutes, although you may be in the department for longer. The treatment itself only takes a few minutes. Most of the appointment is spent getting you into the correct position and doing checks.

Positioning you for treatment

Before your treatment, the radiographers help you on to the treatment couch and position you carefully. They also adjust the height and position of the couch. It is important you are comfortable, as you have to lie as still as possible during the treatment. Let the radiographers know if you are not comfortable.

Young children who are having proton beam therapy may have a general anaesthetic to help them lie still during each treatment. The anaesthetic only lasts for a short time. They may also have an anaesthetic if they are very anxious. Sometimes a play specialist comes to the treatment session to help them keep calm and still.

Before each treatment, you have a CT scan or x-rays in the treatment room. This makes sure you are in the correct position.

You may have more CT or MRI scans during your course of treatment. This is to make sure the treatment is always accurately aimed at the cancer. The radiographers will tell you if you need to have more scans.

When you are in the correct position, the radiographers leave the room and you are given your treatment. There is a camera, so they can see you from outside the room. There is also usually an intercom, so you can talk to them if you need to during your treatment.

During treatment

Most proton beam therapy machines have a part called the gantry. This moves around you to give the treatment from different angles. Or sometimes the treatment couch you are on moves around and the machine stays still. The movements are controlled by the radiographers from outside the room. The radiotherapy machine does not touch you. The treatment itself is painless.

When your treatment session has finished, the radiographers will come and help you off the treatment couch. It is important to wait until they tell you it is ok to move. You can usually go home when the treatment is finished.

Proton beam therapy does not make you radioactive. It is safe to be with other people, including children, throughout your treatment.


Side effects of proton beam therapy

Proton beam therapy may cause fewer side effects than standard radiotherapy. This is because normal cells are exposed to less radiation. The possible side effects will depend on:

  • the area of your body being treated and what structures are close by
  • the amount of proton beam therapy you have
  • other treatments you are having, such as chemotherapy.

Below are some of the side effects of proton beam therapy. They will not affect everyone who has this treatment. Your cancer doctor, specialist nurse or radiographer will explain any possible side effects to you before you start treatment. It is important to tell them about any side effects you get.

General side effects

Side effects usually develop over time. They can include the following:

  • Tiredness – you may feel tired for a few weeks after the treatment has finished.
  • Skin reactions – your skin may become red, dry or itchy. Sometimes the skin can blister or peel. Skin reactions can be worse with proton beam therapy than with standard radiotherapy.
  • Hair loss – you may lose hair in the area being treated.

These side effects are usually mild and disappear a few weeks after treatment has finished.

Specific side effects

Eye tumours

Proton beam therapy for tumours of the eye, including ocular melanoma, may cause side effects including:

  • blurred vision that may last for a few hours
  • swelling of the eyelid
  • irritation of the front of the eye (cornea).

Brain and spinal tumours

Proton beam therapy to the brain or spine may cause side effects including:

Late effects

Most types of radiotherapy cause side effects that develop during treatment and slowly improve after treatment has finished. But sometimes radiotherapy side effects do not go away, or only develop months or years after treatment. These are called late effects (or long-term effects).

The possible late effects of proton beam therapy depend on the area of the body that is treated. Your cancer doctor, specialist nurse or radiographer can give you more information.

Children may get different late effects to adults as they are still growing. Children and teenagers are more likely to develop late effects after proton beam therapy.

As with standard radiotherapy treatment, proton beam therapy can increase the risk of developing a second cancer. But the benefits of treatment usually far outweigh this risk. Your cancer doctor can talk to you about this. The risk of a second cancer is lower with proton beam therapy than with standard radiotherapy treatment.

At the moment, proton beam therapy is only used to treat a few types of cancer. We only know about the potential late effects of treatment for these cancers. More research is needed to find out if proton beam therapy causes late effects when used to treat other types of cancer. If you are worried about the risk of late effects, talk to your cancer doctor or specialist nurse.


Is proton beam therapy available in the UK?

Low-energy proton beam therapy is available at the Clatterbridge Cancer Centre in Wirral to treat tumours of the eye. High-energy proton beam therapy has been available at the Christie Hospital in Manchester from late 2018. It will also be available at University College Hospital in London from 2020.

Some people who need this treatment may be able to have it abroad. The NHS will pay for the treatment (and travel and accommodation) for certain types of cancer. You need to be well enough to travel abroad. Your specialist team will give you more information if proton beam therapy is suitable for the type of cancer you have. When proton beam therapy is available in Manchester and London, the NHS will stop funding treatment abroad.

Proton beam therapy is also available in the UK at private treatment centres. This is not funded by the NHS.

I went to America to have the treatment. I was worried about going, because I wouldn’t have my support network of friends and family, and the medical staff I knew.

Ruth


Benefits and disadvantages of proton beam therapy

Proton beam therapy may cause fewer side effects for some cancers, but we do not know if it is better than standard radiotherapy or other treatments. Proton beam therapy has only been used to treat a few different types of cancer in the UK.

More research is needed before we know if proton beam therapy is as good as, or better than, standard radiotherapy or other treatments.

Possible benefits

  • Proton beam therapy can be used to treat cancers that are close to important structures. These cancers can be difficult to treat with standard radiotherapy or surgery.
  • Proton beam therapy may cause fewer side effects than standard radiotherapy. This is because there is less damage to normal cells.
  • It may be possible to use proton beam therapy to treat cancers that do not normally respond to standard radiotherapy, without increasing side effects.
  • It may be possible to give higher doses of treatment, without increasing side effects.
  • Proton beam therapy helps reduce the risk of developing long-term or late side effects.
  • Proton beam therapy helps reduce the risk of developing a second cancer.

Disadvantages

  • Proton beam therapy is only suitable for certain types of cancer.
  • There are lots of things we do not know about proton beam therapy. More research is needed.
  • People treated with proton beam therapy will still have some side effects.
  • We do not know all the late effects of proton beam therapy.
  • Proton beam therapy is not widely available in the UK.

If proton beam therapy is suitable for you, your cancer doctor and specialist nurse will talk to you about the possible benefits and disadvantages. This will help you decide whether to have proton beam therapy or another type of treatment.

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