What is radiotherapy for brain tumours?
Radiotherapy for brain tumours is the use of high-energy radiation to destroy cancer cells. It is usually delivered using a large machine outside the body, with beams of radiation being targeted as closely as possible to the exact shape of the tumour: known as ‘external beam radiotherapy’ (EBRT).
Occasionally, implant radiation therapy (also known as brachytherapy) is used for brain tumours. ‘Seeds’ are placed inside the cavity left once a brain tumour has been removed or reduced in size using neurosurgery, and these ‘seeds’ gradually release radiation into the surrounding tissue over the following weeks. They do not need to be removed once they have delivered the dose of radiation.
When is radiotherapy used to treat brain tumours?
Radiotherapy is used:
- Instead of surgery when an operation is not possible.
- After surgery in order to kill as many cancerous cells as possible, which may not have been able to be removed during the operation.
Can radiotherapy shrink brain tumours?
Yes, radiotherapy is usually successful at shrinking brain tumours. This is one of the main aims of the treatment because by shrinking the tumour, the pressure inside the skull is reduced and hence symptoms may improve.
Can radiotherapy cure brain tumours?
Radiotherapy can cure some types of small, benign or very slow-growing (low-grade) brain tumours. For brain tumours that are more aggressive, large or diffuse, radiotherapy is more likely to shrink and/or temporarily halt the growth of the tumour rather than cure it.
Can radiotherapy be combined with chemotherapy for brain tumours?
Sometimes, chemotherapy drugs are given either before, at the same time or after radiotherapy in order to enhance the chances of radiotherapy being successful.
What happens during radiotherapy for brain tumours?
A lot of preparation happens before radiotherapy begins. Detailed scans are taken and the radiotherapy team carefully design the radiotherapy schedule and the shape of the target area. This area needs to be designed in three-dimensions, taking into account the need to ensure as little damage as possible to any areas of the brain that are crucial for the patient to function well, whilst killing as many cancer cells as possible.
What is fractionated external beam radiotherapy?
This is the most common type of radiotherapy used for brain tumours. ‘Fractionated’ means that the total dose of radiation is split into fractions and delivered in small bursts of radiation. These fractions are usually delivered daily from Monday to Friday, with the patient being allowed to rest over the weekend. This schedule means that a patient needs to travel to their radiotherapy centre every day for a few weeks, although the actual treatment time each day lasts just a few minutes.
It is important that radiotherapy is delivered to exactly the right place every time. An individual mask is especially made for each patient during the weeks before radiotherapy treatment begins. The mask is used to gently secure them whilst they are lying on a bed that forms part of the radiotherapy machine, and ensures that they can’t accidentally move during the radiotherapy treatment.
The radiotherapy then moves around the patients, delivering short bursts of radiation beams to the exact pattern designed by the radiotherapy team.
What is stereotactic radiotherapy?
Stereotactic radiotherapy (SRT) is sometimes used for small brain tumours, usually those that are only 3-4cm across and in an easily accessible part of the brain, relatively close to the skull. It consists of very precisely focused gamma ray or X-ray beams at higher doses than are used in standard radiotherapy.
The advantage of this treatment is that is can be more closely targeted at a brain tumour than standard radiotherapy and surrounding healthy tissue can be spared, hence reducing the side effects of the treatment.
Stereotactic radiotherapy is usually delivered in one dose, but may be split over a number of visits, for example 2 to 5 sessions: in which case it becomes known as fractionated stereotactic radiotherapy (“fractionated” refers to the fact that the dose has been divided into fractions that are then delivered at those separate sessions).
There are three main ways of delivering stereotactic radiotherapy, each of which uses different equipment and different sources of radiation.
- The Gamma Knife uses beams of highly focused gamma rays
- Devices such as the CyberKnife, designed to treat the tumour by delivering high-energy x-rays formed of particles called photons
- Proton beam therapy is a more targeted treatment, usually reserved for paediatric brain tumours or when the tumour is located in a position where standard radiotherapy might damage crucial, healthy parts of the brain. Historically, patients living in the UK have had to travel abroad for proton beam therapy, often funded by the NHS. However, this treatment is becoming available from 2019 at specialist NHS facilities in Manchester and London, to which you can be referred by your local neuro-oncology team.
What are the side effects of radiotherapy on the brain?
Side effects of radiotherapy can vary, depending on where the tumour is in the brain.
Cancer cells within the target area of the radiation beams are permanently destroyed after radiotherapy, but normal cells can usually repair themselves again, or new cells can be created to replace them. Side effects from radiotherapy can therefore improve over time, though how long this takes will vary between patients.
- Skin redness and soreness. In every radiotherapy department there are nurses who specialise in skin integrity: they can advise about the best way to protect skin and help it to heal.
- Hair loss. It is common to lose hair that is in the direct path of the radiation beams. Most radiotherapy departments are supported by charities that can advise on how to disguise this kind of patchy hair loss using headwear or wigs.
- Oral and dental issues. If the radiation beams pass near the mouth, it is important to have regular dental checks to support oral health. Some patients experience oral thrush, for which medication can be prescribed.
- Nausea. This is more common if the radiation beams pass near the ear and induce a sense of imbalance. Anti-nausea medication can help to manage this side effect.
- Ear issues. If the radiation beams are near the ear it is possible to experience dryness and irritation, which may be relieved by prescription ear drops.
- Fatigue. This is the most common side effect of all types of brain tumour treatment.
- Headaches. It is important that any changes in headaches are reported to the medical team, as sometimes radiotherapy can cause short term swelling to the brain. This is part of a positive immune response to the treatment, but needs careful management to avoid any long term damage. Steroids may be prescribed to reduce the swelling and therefore ease any pressure on the brain.