What is radiotherapy?

Radiotherapy uses high-energy rays, such as x-rays, to treat cancer. It destroys cancer cells in the area where it is given.

Some normal cells in the area can also be damaged by radiotherapy. This can cause side effects. These normal cells are usually able to repair themselves, but cancer cells cannot. As the normal cells recover, the side effects usually get better.

Radiotherapy is always carefully planned by a team of experts. Radiotherapy treatment is continuing to become even more accurate. This allows your team to treat the cancer more effectively, while doing as little harm as possible to normal cells.

Why radiotherapy is given

Many people have radiotherapy as part of their cancer treatment. Radiotherapy is given for different reasons.

Radiotherapy to cure the cancer

This is when radiotherapy is given to try to destroy a tumour and cure the cancer. It is sometimes called radical treatment. You may have radiotherapy on its own or sometimes with chemotherapy (chemoradiation).

Radiotherapy can be given after surgery for some types of cancer, to lower the risk of the cancer coming back. This is called adjuvant radiotherapy.

Sometimes radiotherapy is given before surgery to shrink a cancer and make it easier to remove. You may have it along with chemotherapy. This is sometimes called neo-adjuvant radiotherapy.

Radiotherapy to treat symptoms (palliative radiotherapy)

This is when radiotherapy is given to shrink the cancer and help with symptoms such as pain or coughing. Doctors may suggest this treatment to help control the cancer for longer when curing the cancer is not possible.

Ways of giving radiotherapy

There are two ways of giving radiotherapy:

  • External beam radiotherapy is given from outside the body (externally) by a radiotherapy machine.
  • Internal radiotherapy is when a radioactive material is placed inside the body. It is sometimes called brachytherapy or radioisotope therapy.

How you are given radiotherapy will depend on the type of cancer you have and where it is in the body. Some cancers are treated with both external and internal radiotherapy. Radiotherapy treatment is planned carefully for each person. This means that even if you know someone with the same type of cancer as you, their radiotherapy treatment may be different.


Sometimes chemotherapy is given at the same time as radiotherapy. This is called chemoradiation or chemoradiotherapy. Chemotherapy uses anti-cancer (cytotoxic) drugs to destroy cancer cells. The chemotherapy drugs can make cancer cells more sensitive to radiotherapy. This can help the radiotherapy to work better. This is only helpful for certain types of cancer, so it is not suitable for everyone.

Giving chemotherapy and radiotherapy together can make the side effects of treatment worse. Your doctor, radiographer or specialist nurse can give you more information about chemoradiation and the possible side effects.

Where radiotherapy is given

You usually have radiotherapy in a hospital that has a major cancer treatment centre. This means you may have some treatment at your local hospital, such as surgery or chemotherapy. But you may have radiotherapy at a different hospital.

You usually have external beam radiotherapy as an outpatient. If you are unwell, or are having chemotherapy at the same time, you may need to stay in hospital. In this case, you will go to the radiotherapy department each day from the ward.

If you are having some types of internal radiotherapy, you may have to stay in hospital for a few days.

Back to Radiotherapy explained

Before your radiotherapy

Before you start radiotherapy, your team will explain what your treatment involves and how it may affect you.

Masks for radiotherapy

During most types of radiotherapy to the brain, head or neck, you wear a mask to help you keep still.

Your radiotherapy team

You will meet many different specialists from your radiotherapy team. You may see them before, during and after radiotherapy treatment.

After your radiotherapy

It can take time to recover from radiotherapy. Support is there if you have any problems.