What is radiotherapy?

Radiotherapy uses high-energy rays to destroy the cancer cells, while doing as little harm as possible to normal cells. It is an important treatment for head and neck cancers.

Radiotherapy can be used on its own, but is often given in combination with chemotherapy. This is called chemoradiation.


Chemoradiation is a very effective treatment for head and neck cancers. It is often the main treatment for locally advanced head and neck cancers. But it can cause severe side effects so it is not be suitable for everyone.

Chemoradiation may be used to treat head and neck cancers:

  • that cannot be removed with surgery
  • that are in harder-to-reach areas, such as nasopharyngeal cancer or oropharyngeal cancer
  • when surgery could cause severe changes to speech or swallowing
  • to reduce the risk of the cancer coming back (adjuvant treatment) after surgery

We have more information about chemoradiation.

Radiotherapy for early-stage cancers

Radiotherapy can be used on its own to treat cancers that are small and have not spread. It is often used for cancers in harder-to-reach areas, such as the back of the mouth or throat. Radiotherapy may also be used when surgery could seriously affect important functions, such as speech and swallowing.

Radiotherapy for locally advanced cancers

If a cancer is bigger, or is affecting other tissues nearby (locally advanced cancer), radiotherapy is usually combined with other treatments. It may be given:

  • after surgery (with or without chemotherapy) to destroy any remaining cancer cells and reduce the risk of cancer coming back
  • in combination with chemotherapy (chemoradiation), without surgery
  • in combination with the targeted therapy drug cetuximab
  • to reduce symptoms (palliative radiotherapy).

Radiotherapy after surgery (adjuvant radiotherapy)

If you have surgery for some early and locally advanced cancers, you are usually given radiotherapy afterwards. This is to reduce the risk of the cancer coming back. It is called adjuvant radiotherapy. Sometimes chemotherapy and radiotherapy are given together after surgery. This called adjuvant chemoradiation.

If you need adjuvant treatment, your specialist team will decide whether radiotherapy or chemoradiation is best for your situation.

Radiotherapy and cetuximab

Some people may be given radiotherapy in combination with a targeted therapy drug called cetuximab. This is usually when they are not well enough to cope with the side effects of chemoradiation. Or they may have other health problems that could be made worse by chemotherapy.

Palliative radiotherapy

Sometimes it is not possible to cure a cancer, and the main aim of treatment is to relieve symptoms. This is called palliative treatment. Palliative radiotherapy may be used to:

  • stop bleeding from a tumour
  • shrink a tumour that is causing swallowing or breathing difficulties
  • relieve symptoms if the cancer has spread to other parts of the body, such as the lungs or bones.

Radiotherapy side effects

Your nurse or doctor will explain the likely side effects of your radiotherapy treatment. They will explain how your side effects can be managed. If you are having chemoradiation the side effects are usually more severe.

How radiotherapy is given

Radiotherapy is usually given from outside the body as external-beam radiotherapy. A beam of x-rays is directed at the cancer from a large machine called a linear accelerator.

External-beam radiotherapy

External-beam radiotherapy is given in the hospital radiotherapy department. It can be used in different ways. It may be given:

  • Monday to Friday, with a rest at the weekend (this is the most common method)
  • more than once a day
  • every day, including at the weekend.

Treatment may take 4 to 7 weeks, depending on the type and size of the cancer. Your radiotherapy doctor (clinical oncologist) or specialist nurse will discuss the treatment with you.

We have more information about external-beam radiotherapy.

Intensity-modulated radiotherapy (IMRT)

This is the most common type of external-beam radiotherapy used for head and neck cancers. It uses several beams of radiation that come from different directions. A special attachment on the radiotherapy machine arranges the radiation beams to match the shape of the cancer. Shaping the beams lets the doctors give higher doses of treatment to the cancer and lower doses to the surrounding healthy tissue.

Research has found that, for some people, having IMRT rather than standard radiotherapy may reduce some long-term side effects, such as a dry mouth. This is because the radiotherapy shapes the beams to avoid the salivary glands, which is where saliva (spit) is produced.

Some people may have frequent scans during their treatment. This is to make sure the treatment accurately targets the treatment area. Changes can be made if needed, for example if you lose weight during treatment.

Conformal radiotherapy (CRT)

This is a simpler type of external-beam radiotherapy. It may be used to give lower doses of radiotherapy.

Planning your radiotherapy

To make sure your radiotherapy is as effective as possible, it has to be carefully planned. Planning makes sure the radiotherapy rays are aimed precisely at the cancer and cause the least possible damage to the surrounding healthy tissues. The treatment is planned by a specialist doctor called a clinical oncologist.

Radiotherapy planning is usually done during one visit to the radiotherapy department. It usually takes about 2 hours. Sometimes you may need to make more than one visit.

To start with, you meet the radiographers (experts in giving radiotherapy). They can answer any questions you have.

Before you have your treatment planned you will need to have a radiotherapy mask made.

Radiotherapy masks

It is important that you lie still, in exactly the same position, for each treatment. To help you do this, you wear a clear plastic mesh mask for each session of radiotherapy. The mask is designed so you can see and breathe normally while wearing it. It is sometimes also called a mould, head shell or cast.

The mask holds your head and neck as still as possible. You have it on for up to about 15 minutes at a time. It fits tightly but should not be uncomfortable. Most people soon get used to it. But it is important to talk to the radiographer, mould room technician or your specialist nurse if you find it difficult to wear the mask. They can suggest things that might help.

After your mask is made

Once you have your mask, you will have a CT scan of the area to be treated. The radiographers take measurements to plan the treatment specifically for you. Some people also have an MRI scan as part of their radiotherapy planning. Learn more about the scans.

The radiographer’s measurements and the information from the scans are entered into the radiotherapy planning computer. Your doctors then use this to plan your treatment precisely.

Sometimes, marks might be drawn on your mask. These help the radiographer position you accurately before each treatment.

We have more information about masks for radiotherapy

Tracheostomy tube

Very occasionally, radiotherapy to the mouth or throat can cause swelling in tissues around the airways. This can make breathing difficult. If this is likely to happen, your doctors arrange for you to have a small opening made in your windpipe before you have radiotherapy. This is called a tracheostomy (or stoma) and allows you to breathe comfortably. A tracheostomy is usually temporary.

Having radiotherapy

Before each treatment session, the radiographer positions you on the treatment couch and carefully fits your mask. The treatment only takes a few minutes.

During this time, you are left alone in the room, but the radiographer can see you from the next room. If you are worried about anything, you can speak to them through the intercom and they will come in to help you. If there is not an intercom in the room, the radiographers will tell you how you can get their attention if you need to.

In some treatment rooms, you can listen to music to help you relax during your treatment. If you would like to listen to your own music, ask your radiographers if this is possible.

You do not feel anything during the treatment. Some radiotherapy machines make a small beeping noise. This is just so that you know when the treatment is starting and when it has finished.

External radiotherapy does not make you radioactive. It is safe for you to be with other people throughout your treatment, including children.


Getting support

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About our information

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Dr Chris Alcock, Consultant Clinical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.