Radiation therapy for bowel cancer

Radiation therapy for bowel cancer (also known as radiotherapy) uses radiation, such as protons, to kill cancer cells. The radiation is targeted to the specific site of the cancer, and treatment is carefully planned to do as little harm as possible to your normal body tissue near the cancer.

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When is radiation therapy used?

Commonly, radiation therapy is used before surgery for locally advanced rectal cancer. It is often combined with chemotherapy (called chemoradiotherapy or chemoradiation).

This is because chemotherapy makes cancer cells more sensitive to radiation therapy, and reducing the number of cancer cells will make it easier for the surgeon to completely remove the tumour. Radiation therapy is not used to treat early colon cancer.

How does radiation therapy work?

Radiation therapy can be delivered in different ways, including IMRT (intensity-modulated radiation therapy) and VMAT (volumetric modulated arc therapy). These techniques deliver a dose to the affected area without damaging surrounding tissue. These improvements have reduced the side effects from radiation therapy.

During treatment, you will lie on a treatment table under a machine called a linear accelerator. Each treatment takes only a few minutes, but a session may last 10–20 minutes because of the time it takes to set up the machine.

If radiation therapy is given with chemotherapy, you will have it once a day for 5–6 weeks. You may have a shorter course of radiation therapy if it is given by itself, usually for five days, Monday to Friday. To find out more, call 13 11 20 for a copy of Understanding Radiation Therapy, or download a copy from this page.

Side effects of radiation therapy

Common side effects of radiation therapy include:

People react to treatment differently, so some people may have few side effects, while others have more. Your treatment team will give you advice about how to manage radiation therapy side effects.

Fertility and sexual function after radiation therapy

Radiation therapy to the pelvis and rectum can affect your ability to have children (fertility) and sexual function. Below are some ways radiation therapy may affect men and women.

For men

  • Radiation therapy can damage sperm or reduce sperm production. This may be temporary or permanent.
  • Most doctors suggest that men use contraception or abstain from unprotected sex during and after radiation therapy for one month.
  • You will be able to store sperm at a hospital or fertility clinic before treatment starts. Talk to your doctor about this.
  • Because radiation therapy can damage blood vessels and nerves that produce erections, some men may have erection problems. Your doctor may prescribe medication or refer you to a specialist clinic to manage this problem.

For women

  • Radiation therapy may lead to damage and narrowing of the vagina, making sexual intercourse painful. The use of a vaginal dilator can help to gradually widen the entrance and prevent the side walls sticking together. Ask your doctor or a physiotherapist for advice on how to use a dilator.
  • In some cases, radiation therapy can affect the ovaries and stop them producing female hormones. This can cause menopause and infertility. Menopause can be managed by hormone replacement therapy, which is safe for rectal cancer. After menopause you will not be able to conceive a child. Share your feelings about any fertility issues with your partner, a counsellor or a fertility specialist.

To find out more, call Cancer Council 13 11 20 and ask for free copies of the Fertility and Cancer, and Sexuality, Intimacy and Cancer booklets, or download digital copies from this page.

Video: What is radiation therapy?

Watch this short video to learn more about radiation therapy.

This information was last reviewed in February 2017
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