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This information has been written to help you understand more about prophylactic cranial radiotherapy (PCR). It should ideally be read with our information about radiotherapy.
Prophylactic (preventative) cranial (head) radiotherapy (x-ray treatment) involves giving radiotherapy to a person’s head to prevent or delay the possible spread of cancer cells to the brain.
PCR is usually given to people who have a type of lung cancer known as small cell lung cancer (SCLC). It may also be given to some people with acute lymphoblastic leukaemia (ALL).
In SCLC it is given when the cancer has not spread to other parts of the body, and has responded well to previous treatments. In SCLC there is a risk that tiny numbers of cancer cells may escape from the lung and spread to the brain. These would be too small to be detected by scans but in time would grow to form secondary cancers in the brain. Your specialist may recommend PCR to try to prevent this from happening. Chemotherapy may not be as effective at treating cancer cells that have spread to the brain. This is because the brain is protected by a membrane called the 'blood-brain barrier' that stops a lot of chemotherapy drugs from getting to the brain.
Doctors think that prophylactic cranial radiotherapy may also be useful for people with SCLC who have more advanced disease. This is now being looked at in clinical trials. Your specialist can advise you whether PCR is an appropriate treatment for you and whether you may be able to take part in any research trials.
In acute lymphoblastic leukaemia, when PCR is given, it is usually after chemotherapy. Again, this is because the chemotherapy drugs may not have been effective in treating any cells that may have spread to the brain. These cells may be too small to show up on a scan or to cause symptoms. So, PCR is given as a preventative treatment to stop the leukaemia from causing problems in your brain later on. Sometimes chemotherapy is given into the spinal fluid (intrathecal chemotherapy) as well as, or instead of, PCR.
Radiotherapy treats cancer by using high-energy rays that destroy cancer cells while doing as little harm as possible to normal cells. PCR aims these high-energy x-rays at the head and is given by a radiotherapy machine. This is known as external beam radiotherapy. The treatment is given in the hospital radiotherapy department.
Your radiotherapy is carefully planned to make sure that you get the maximum benefit. This may involve a few visits to the radiotherapy department before treatment starts. As radiotherapy is planned very precisely to treat exactly the right area, it is important to keep that part of the body as still as possible. You will be asked to lie back with your head on a firm headrest. A soft clamp is fitted to each side of your head to hold it steady during treatment. Alternatively a see-through perspex device called a radiotherapy mask, mould or shell will be made. This fits round your head and helps you keep still during treatment.
Prophylactic cranial radiotherapy is given as a series of short daily treatments in the radiotherapy department, using equipment similar to a large x-ray machine. Each treatment lasts for only a few minutes. The treatments are usually given from Monday to Friday. The number of radiotherapy sessions given will vary depending upon the individual situation. You may hear the doctor use the term 'fractions' to describe your daily treatments.
Each person’s reaction to radiotherapy is different. Some people have very few side effects, while others may experience more. Usually the side effects of PCR are mild. If you notice any effects which you think may be due to PCR, but are not listed here, please let your doctor, nurses or radiographers know.
Hair loss Your hair may start to fall out three weeks after your first treatment. Most hair loss is temporary. Hair usually starts to grow back within 2−3 months of finishing treatment. Sometimes it grows back with a slightly different colour and texture and perhaps not as thickly as before.
Tiredness You may find that you feel very tired during radiotherapy. This can often be made worse by having to travel to hospital each day. Listen to your body and allow yourself extra time to rest, perhaps by taking a nap during the day. Tiredness can continue for some months after treatment has finished.
Drowsiness (somnolence) This can occur throughout the period of radiotherapy treatment and also for a time after the treatment has ended. It is usually mild. This period of tiredness is at its worst about two weeks after treatment starts but gradually begins to improve. It can sometimes get worse again around 4−6 weeks after treatment finishes, but will get better a week or so later.
Headache Occasionally some people experience headaches during treatment. This usually happens in the first few days after starting PCR. It is important to let the staff looking after you know if you have a headache. Your doctor may prescribe painkilling drugs and sometimes steroid tablets.
Feeling sick You may feel sick (nauseous) but this is uncommon and can usually be effectively treated by anti-sickness drugs (called anti-emetics). Your doctor can prescribe these. If your sickness is not controlled, or if it continues, tell your doctor. They can prescribe other anti-sickness drugs that may be more effective.
Loss of appetite You may find that food tastes different. If you don't feel like eating, you can replace meals with nutritious, high-calorie drinks. These are available from most chemists and can also be prescribed by your GP. A dietitian or specialist nurse at your hospital can give advice on dealing with loss of appetite.
Skin changes Some people develop what is known as a 'skin reaction' while having external radiotherapy, although with PCR any skin changes are usually mild. People with pale skin may find that the treatment area becomes red, hot, sore or itchy. People with dark skin may find that their skin becomes darker. The degree of reaction depends on the area being treated and the individual person’s skin type. Staff in the radiotherapy department will be looking for this reaction but let them know if you see any changes or feel any soreness.
The staff will also be able to give advice on skin care. This may vary from one hospital to another and with the dose of radiotherapy that is being given. You might be advised not to wash the treatment area at all while you are having treatment, or you may be told that it is best to use only tepid water and then dry it by patting gently with a soft towel.
Because your skin will be sensitive during and after treatment it is best not to overexpose it to the sun or cold winds. Try wearing a soft cotton or silk scarf or a hat to cover your head when you go outside. It is also important to cover the treated area if you go out in strong sunshine for at least the first year after radiotherapy.
You may find the idea of radiotherapy to the head worrying. At a time like this it is not unusual to have many different emotions, including anxiety and fear. These are normal reactions and are part of the process that many people go through in trying to come to terms with their cancer and its treatment.
People often worry that PCR may affect their memory or their ability to think clearly, but with the low doses of radiotherapy used for PCR, this would be very unlikely. It can be useful to discuss any worries you have with your doctors or nurses. Close friends and family members can also offer support.
This section has been compiled using information from a number of reliable sources including:
For further references, please see the general bibliography.
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