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This information is about prophylactic cranial radiotherapy (PCR). PCR is also sometimes called PCI, which stands for prophylactic cranial irradiation. It should ideally be read with our information about radiotherapy|.
Prophylactic (preventative) cranial (head) radiotherapy (x-ray treatment) is when radiotherapy is given to a person’s head to prevent or delay the spread of a cancer to the brain (secondary brain cancer|).
PCR is usually given to people who have a type of lung cancer called small cell lung cancer (SCLC).| It may also be given to some people with acute lymphoblastic leukaemia (ALL)|.
PCR may also be effective at reducing the risk of secondary brain cancer in people who have non-small cell lung cancer (NSCLC)|, but this is still being researched.
People with SCLC may have PCR when the cancer has not spread to other parts of the body and has responded well to previous treatments. If you have SCLC, there is a risk that tiny numbers of cancer cells may escape from your lung and spread to your 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 prevent this happening. PCR treats the whole brain.
PCR may be more effective than chemotherapy| at treating cancer cells that may 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.
Studies show that PCR helps people with SCLC live longer when it is given to those who are in complete remission and have no signs of the cancer. It reduces the chance of developing a secondary cancer in the brain.
PCR may also be useful for people with SCLC who have more advanced disease. Your specialist can advise you whether PCR is an appropriate treatment for you.
When PCR is given to people with ALL, it is usually given 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 PCR, or instead of it.
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 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 may be fitted to each side of your head to hold it steady during treatment.
Alternatively, a see-through perspex device or a plastic mesh| may be used to make a mould that fits around your head. The mould is used to help you stay in position during radiotherapy.
PCR 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–Friday. The number of radiotherapy sessions will vary depending upon your 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 that you think may be due to PCR but are not listed below, let your doctor, nurses or radiographers know.
Your hair may start to fall out about three weeks after your first treatment. Most hair loss| is temporary. Hair usually starts to grow back 2−3 months after you finish treatment. Sometimes it grows back with a slightly different colour and texture, and it may not be as thick as before.
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 for a nap during the day. Tiredness may continue for about three months after treatment has finished.
This can occur throughout your radiotherapy and for a time after the treatment has finished. It is usually mild. Drowsiness is at its worst about two weeks after treatment starts, but will gradually begin to improve. It can sometimes get worse again around 4−6 weeks after treatment finishes, but will get better a week or so later.
Occasionally, some people experience headaches during treatment. This usually happens in the first few days after starting PCR. It's important to let the staff looking after you know if you have a headache. Your doctor may prescribe painkillers| and sometimes steroid tablets|.
You may feel sick (nausea|) but this is uncommon and can usually be effectively treated with anti-sickness (anti-emetics) drugs. Your doctor can prescribe these. If your sickness isn't controlled, or if it continues, tell your doctor; they can prescribe other anti-sickness drugs that may be more effective.
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 you advice.
Some people develop what is known as a 'skin reaction' while having external radiotherapy. With PCR, any skin changes are usually mild, but your skin may become sore behind the ears. 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 any skin reaction depends on the area being treated and your skin type. Staff in the radiotherapy department will be looking for this reaction, but let them know if you notice any changes or feel any soreness.
The staff will also be able to give advice on skincare. This may vary from one hospital to another and depend on 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's best to use only tepid water and to dry yourself by patting gently with a soft towel.
Because your skin will be sensitive during and after treatment, it's best not to over-expose 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 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 this is very unlikely with the low doses of radiotherapy used for PCR. It can be useful to discuss any worries you have with your doctors or nurses. Family members and close friends can also offer support.
This section has been compiled using information from a number of reliable sources including:
For answers, support or just a chat, call the Macmillan Support Line free (Monday to Friday, 9am-8pm)
If you have any questions about cancer, need support or just want someone to talk to, ask Macmillan.