Prophylactic cranial radiotherapy (PCR)

PCR is usually given to people who have a type of lung cancer called small cell lung cancer (SCLC).

It may sometimes be given to people who have acute lymphoblastic leukaemia (ALL) and lymphoblastic lymphoma, if their doctor thinks there is a risk of the leukaemia affecting the brain.

PCR may help reduce the risk of secondary brain tumours in people who have non-small cell lung cancer (NSCLC), but research suggests there is no overall benefit, so it is not usually given.

With SCLC, there is a risk that tiny numbers of cancer cells may spread from the lung to the brain. These would be too small to be seen by scans. But over time, they would grow into secondary cancers in the brain. Your specialist may recommend PCR to stop this happening. It can help people with SCLC live longer.

If chemotherapy has worked well, people with SCLC may have PCR in these situations:

• If the cancer has not spread to other parts of the body (limited-stage SCLC), they may have PCR after chemoradiation.
• If the cancer has spread further (extensive-stage SCLC), they may have PCR and also radiotherapy to the chest.

PCR treats the whole brain. It is given because chemotherapy is not good 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. This stops a lot of chemotherapy drugs from getting to the brain.

Each person’s reaction to radiotherapy is different. Some people have very few side effects, and other people have more. Usually the side effects of PCR are mild.

Radiotherapy can make you tired, especially if you have to travel a long way for treatment each day. Tiredness can continue for several months after treatment has finished.

Somnolence is an extreme tiredness some people get after radiotherapy to the brain. It happens about 4 to 8 weeks after treatment finishes. You may:

• have very little energy
• feel sleepy
• spend a lot of time sleeping.

This slowly gets better over a few weeks.

Some people have headaches during treatment. This can happen in the first few days after starting PCR. It is important to tell the staff looking after you if you have a headache. Your doctor may prescribe painkillers, or sometimes steroids.

You may feel sick (nauseous), but this is not common. It can usually be treated with anti-sickness drugs (anti-emetics). Your doctor can prescribe these. Tell your doctor if your sickness:

• is not controlled
• continues.

They can prescribe other anti-sickness drugs that may be more effective, or steroids.

The hospital staff will advise you on how to look after your skin. Do not put anything on the treated area of your skin before checking with your nurse or radiographer.

Wash your hair or scalp gently with lukewarm or cool water. Gently pat your hair or scalp dry with a soft towel. Do not rub it, and do not use a hair-dryer.

You may have a mild skin reaction after PCR. Your skin may become red and itchy and sore behind the ears. After treatment, your skin may become darker. Staff in the radiotherapy department will check you for a reaction but tell them if you notice any changes or feel any soreness.

If you have a skin reaction, wear a scarf or hat to protect your head from the sun or cold until it gets better. Avoid exposing your head to the sun during treatment and for at least a year afterwards. Cover your head or use sun-cream with a sun protection factor (SPF) of at least 30.

Radiotherapy to the brain may affect a person’s memory and their ability to think or reason (cognitive function). After treatment, they may have short-term memory loss or difficulty concentrating.

Your doctors can explain more about this. They will think about the risk of this happening compared to the benefit of PCR. The effects on memory are more likely to happen in older people who have PCR.