Radiotherapy of Medulloblastoma for children
This information has been produced to provide details about radiotherapy of medulloblastoma and aims to answer some of the questions often asked by patients and their carers.
We hope you will find this helpful. If you have any further questions relating to your treatment, please do not hesitate to ask your radiographer or your oncologist at the Northern Centre for Cancer Care (NCCC).
We give radiation treatment (radiotherapy) after surgery or chemotherapy because the disease always comes back if we do not.
The treatment has to be planned with great care and it is successful for many, but unfortunately not all, patients. The total radiation dose has to be spread out over quite a long time to make the individual treatments safe. We give treatment every day for about seven weeks (usually excluding weekends and bank holidays). At each session, the patient spends about twenty minutes in the treatment room. Most of this time is spent getting the patient into the correct treatment position.
Radiotherapy does not hurt, the machine does not touch the patient, and it is rather like having an ordinary x-ray. We have to treat the whole brain and the spine. This means that the patient must lie very still on their front. To make this easier, we make a facemask for each patient. Lying still can be very difficult for some children, specially very young ones.
Occasionally we have to use a general anaesthetic. Several small permanent skin marks (tattoos) are made on the skin to act as reference points for the radiotherapy. This involves a drop of black ink on the skin and a small scratch on the skin surface with a needle. This is usually not felt at all but at worst is mildly uncomfortable.
Occasionally when we are treating the brain, some patients experience a strange smell. This does not happen for everyone. Also a buzzing noise can be heard which is the machine working.
How will radiotherapy be given?
How will radiotherapy be given?
Medulloblastoma starts in the back part of the brain (the cerebellum) but it can spread to the whole of the brain and into the spinal cord. Initially each treatment will be to the whole brain and spine. This is phase one.
Phase two treatments are given to the place where the tumour was found originally. If a scan shows that the disease has spread to anywhere else in the brain or spine, we give extra treatment to those places as well.
There are always side effects to radiotherapy. We can relieve most of them but sometimes not completely. Some of the side effects happen immediately, some of them happen soon after we finish treatment, and some take a longer time to show.
Immediate side effects
Sometimes the treatment causes the brain to swell slightly (at its greatest about ten days into treatment). This is usually not noticeable because pressure on the brain has been eased by removing the tumour or by relieving it with a shunt (a pressure relieving device). If swelling causes problems, we give a small dose of steroids.
We cannot prevent patients losing their hair. It starts to fall out after about two weeks of treatment and is more or less all gone by the end. It usually starts to grow back about three months after treatment. Sometimes, hair doesn't grow back fully over the lower part of the back of the head (this is where the tumour was originally and will have had a high dose of radiation).
A sore throat can be a problem, starting about three weeks after treatment begins. Medication can be prescribed to relieve this.
Some patients feel sick and vomit because part of the radiation on the back passes on through their stomach. When this happens, we can control the problem with anti-sickness drugs.
Side effects after completing treatment
A long course of radiotherapy can make the patient very tired. This is most noticeable near the end of the treatment and just afterwards. There might be a particularly sleepy spell starting four to six weeks after treatment ends and going on for two to six weeks or even longer.
There may be occasional headaches or bouts of sickness. These side effects can be very worrying at the time but usually they all settle down within six to nine months.
Long-term side effects
These are the hardest to predict and, unfortunately, when they do happen they are permanent.
Young children will not grow to be as tall as they would have been. This is because radiation affects the gland that controls growth (the pituitary gland). Also, radiation affects the bones of the spine (the vertebrae) and they do not grow as they would have done. Growth hormone can improve things. However, a young child may be several inches shorter when grown-up than without the illness and the treatment.
The pituitary gland also controls development. Radiotherapy for children may make puberty start earlier. Endocrinologists (doctors specialising in hormones) will help deal with any problems. They will also monitor the thyroid gland as this can be affected by radiotherapy.
Girls’ fertility is occasionally affected due to the effect of radiation on their ovaries. Options for overcoming infertility can be discussed at the appropriate time. Boys are not affected because their testicles are well away from the treatment area.
It is possible for radiotherapy to affect learning ability, especially when very young children’s brains are treated. Research indicates that by three or four years after treatment young children don’t learn new information and skills quite as easily. We need to know exactly what the effects are and how we can support and help people who have been affected. When it is possible, one of our neuropsychologists may see the patient before treatment starts and yearly afterwards.
Development of cataracts. This may occur because of unavoidable radiation to the eye. Fortunately cataract surgery today is very straightforward and successful.
It is usual for chemotherapy to be given before, during or after radiotherapy for medulloblastoma. One of the chemotherapy drugs (cisplatin) can affect the hearing, especially after radiotherapy. The hearing is tested regularly during chemotherapy to try and reduce the chance of impaired hearing.
We are finding that, very rarely, children who have had radiotherapy for one tumour can develop another type of tumour some years later. Your oncologist will explain this during the consent process. During follow up we will be looking out for all these problems.
Leaflet to download
You can download the information on this page as a PDF file: