What is proton beam therapy?
Proton beam therapy (PBT) is a type of radiotherapy. Radiotherapy usually uses high energy beams of radiation to destroy cancer cells, also called photons. Radiation is essentially a way that energy or heat moves around. A nice example is sunshine! Being treated with invisible rays sounds pretty sci-fi but the reality is it’s a very effective treatment designed to kill cancer cells, while causing as little harm as possible to your normal cells.
PBT works in the same way but uses tiny parts of atoms called protons instead.
Like other forms of radiotherapy, the aim of PBT 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.
Photons vs protons
PBT uses tiny parts of atoms called protons instead, rather than photons. Protons are better at precisely targeting a tumour. The energy hits mainly the tumour site and, unlike photons, does not deliver a dose beyond the tumour. This means there is less damage to healthy tissue and it's thought that it causes fewer side effects.
Why would I have PBT rather than radiotherapy?
Doctors may recommend proton therapy if you have a tumour that is close to delicate parts of the body, such as the brain or spinal cord.
There is no difference in the biological effectiveness of protons versus photons in terms of the damage they cause to cancer cells - but if your cancer is complicated or in a delicate place, PBT could be better at delivering the dose more effectively.
It’s only used if your doctor thinks it’s specifically right for you. If they believe it is, they’ll refer your case to a panel of experts who will approve it.
How is proton beam therapy given?
People having proton beam therapy are treated as outpatients. Treatments are usually given daily from Monday to Friday with weekends off. The proton treatment course usually lasts about six to seven 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.
Proton beam therapy is painless and treatments usually last up to about one hour in total.
Where will I have it?
Up until recently, PBT was only available at special treatment centres abroad. The NHS paid for treatment, flights and accommodation, usually to the USA.
Now, there are new PBT centres opening in the UK.
You'll need to talk to your consultant about the next steps - they'll be able to talk you through what to expect and where you might receive this treatment.
Updated March 2018, next review due 2021.