Radiotherapy is the use of high-energy rays, usually x-rays and similar rays to treat cancer.

What is radiotherapy?

Radiotherapy uses high-energy rays to destroy the cancer cells, while doing as little harm as possible to normal cells.

Radiotherapy may be given to the anus and rectum after surgery. Nearby lymph nodes may also be treated. Radiotherapy given to this part of the body is called pelvic radiotherapy. The aim is to reduce the risk of the cancer coming back in that area.

The treatment is given as a series of short, daily sessions (called fractions) over a few weeks. You have treatment from a machine similar to a large x-ray machine. Radiotherapy only treats the area of the body that the rays are aimed at. It does not make you radioactive.

If the cancer has spread to other areas of the body, radiotherapy may be given to a specific area to control symptoms, such as bleeding or pain. In this case, you might only need a few days of treatment or just a single dose.

Pelvic radiotherapy side effects

You may have side effects during your treatment. These usually disappear gradually over a few weeks or months after treatment finishes. Your radiotherapy team will let you know what to expect. Tell them about any side effects you have. There are often things that can help.

Some possible side effects are:

  • dry, sore, itchy skin in the area being treated
  • needing to pass urine more often
  • diarrhoea or loose stools
  • tiredness (fatigue).

We have more information about coping with the side effects of pelvic radiotherapy.

How we can help

Clinical Information Nurse Specialists
Our Cancer Information Nurse Specialists are dedicated cancer nurses available to talk to on our Macmillan Cancer Support Line. 
0808 808 00 00
7 days a week, 8am - 8pm
Email us
Get in touch via this form
Chat online
7 days a week, 8am - 8pm
Online Community
An anonymous network of people affected by cancer which is free to join. Share experiences, ask questions and talk to people who understand.
Help in your area
What's going on near you? Find out about support groups, where to get information and how to get involved with Macmillan where you live.