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Having radiotherapy

Find out how you have radiotherapy for cancer of unknown primary (CUP), and the common side effects.

Radiotherapy uses high energy x-rays to treat cancer cells.

Why you might have it

Most people with CUP have radiotherapy to help control symptoms caused by the cancer, such as pain or breathing problems. This is called palliative treatment.

In some cases, you might have radiotherapy to try to cure the cancer. For example, you might have radiotherapy if the secondary cancer is in the lymph nodes in the neck, and it's likely that the cancer started in your head or neck. You may have the radiotherapy on its own or after surgery. 

Your doctor will talk to you about why they are suggesting you have radiotherapy and what the aim of treatment is.

How you have it

You have radiotherapy in the hospital radiotherapy department. You might have it as a one off treatment or once a day for a few days if you are having it to control symptoms. Or you might have it as a course of treatments over a number of weeks if you are having it to try to cure the cancer.

The radiotherapy team carefully plan your treatment before you start. This means working out how much radiation you need to treat the cancer and exactly where you need it.

The radiotherapy room

Radiotherapy machines are very big. They rotate around you to give you your treatment. The machine doesn't touch you at any point.

Before you start your course of treatment your therapy radiographers explain what you will see and hear. In some departments the treatment rooms have docks for you to plug in your music player. So you can listen to your own music.

Photo of a linear accelerator

During the treatment

You need to lie very still on your back. Your radiographers might take images (x-rays or scans) before your treatment to make sure that you're in the right position. The machine makes whirring and beeping sounds. You won’t feel anything when you have the treatment.

Your radiographers can see and hear you on a CCTV screen in the next room. They can talk to you over an intercom and might ask you to hold your breath or take shallow breaths at times. You can also talk to them through the intercom or raise your hand if you need to stop or if you're uncomfortable.

You won't be radioactive

This type of radiotherapy won't make you radioactive. It's safe to be around other people, including pregnant women and children.

Travelling to radiotherapy appointments

Tell the radiotherapy department if you prefer treatment at a particular time of day. They can try to arrange this.

Car parking can be difficult at hospitals. It’s worth asking the radiotherapy unit staff:

  • if they can give you a hospital parking permit
  • about discounted parking rates
  • where you can get help with travel fares
  • for tips on free places to park nearby

If you have no other way to get to the hospital, the radiotherapy staff might be able to arrange hospital transport for you. But it might not always be at convenient times. To see if you're eligible they usually work it out based on your earnings or income.

Some hospitals have their own drivers or can arrange ambulances. Some charities offer hospital transport.

Side effects

The side effects of radiotherapy depend on which part of your body is treated. For example, radiotherapy to the neck can cause a sore throat and difficulty swallowing. Whereas radiotherapy to the tummy (abdomen) or pelvis, tends to make you feel sick or have diarrhoea. 

You might feel tired while having radiotherapy. This is more likely if you are having treatment over a number of weeks.

The side effects tend to come on as you go through your course of treatment. If you have a short course of treatment of only a few days, you might have very few side effects. The side effects gradually disappear in the days after your treatment has finished.

Last reviewed: 
12 Oct 2017
  • Radiotherapy in Practice: External Beam Therapy
    PJ Hoskin
    Oxford University Press, 2006

  • Cancer: Principles and Practice of Oncology (10th edition)
    VT DeVita, TS Lawrence, SA Rosenberg
    Lippincott, Williams and Wilkins, 2015

  • Cancer and its Management (7th edition)
    J Tobias and D Hochhauser
    Wiley-Blackwell, 2015

  • Overview of the classification and management of cancers of unknown primary site

    J Hainsworth and others ​

    UpToDate, 2017

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