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Radiotherapy treatment

External radiotherapy uses high energy waves similar to x-rays to destroy cancer cells. 

You have radiotherapy in a hospital radiotherapy department. You go to the radiotherapy department from your ward if you’re already in hospital.

When do you have radiotherapy for anal cancer?

You might have radiotherapy:

  • combined with chemotherapy (chemoradiotherapy) 
  • to relieve symptoms of anal cancer that has spread (advanced anal cancer)


Chemotherapy combined with radiotherapy (chemoradiotherapy) is the main treatment for anal cancer that hasn't spread to other parts of the body.

Doctors know from research that this is a better treatment for anal cancer than surgery. If chemoradiotherapy is successful, you won't need a permanent colostomy.

For cancer that has spread

Radiotherapy can relieve the symptoms of advanced anal cancer, such as pain. It aims to shrink or control the growth of the cancer for a period of time. This is called palliative radiotherapy.

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 Open a glossary item 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

Before each treatment session

You might have to have a full bladder for radiotherapy to the anus. This means drinking a certain amount of water every day before your treatment. You then wait for your bladder to fill before you go into the radiotherapy room. Your radiographers let you know at your planning scan whether you'll be doing this. 

For some people having a full bladder for radiotherapy to the anus can help reduce the dose of radiation to normal healthy tissues. 

During the treatment

Your radiographers will help you to get onto the couch.

You'll be in the same position that you were in for your planning scan. This is usually lying face down with a special cushion underneath you. You might have to raise your arms over your head. 

You need to lie very still. 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 will ask you to raise your hand if you need anything but it is important to stay as still as possible. 

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 of treatment

Side effects of radiotherapy for anal cancer can include feeling tired, sore skin around the anus and groin, or bladder irritation. You may also need to open your bowels frequently, or may feel sick.

Last reviewed: 
30 Apr 2019
  • Neoplasms of anal canal and perianal skin
    D. Leonard and others
    Clinical Colon Rectal Surgery, 2011. Volume 24, Pages 54-63

  • Anal cancer: ESMO-ESSO-ESTRO Clinical Practice Guidelines for diagnosis, treatment and follow-up
    R. Glynne-Jones and others
    Annals of Oncology 2014. Volume 25, Pages iii10-iii20