Radiation therapy cancer treatment

Radiation therapy (also known as Radiotherapy) uses a controlled dose of radiation to kill cancer cells or damage them so they cannot grow, multiply or spread. The radiation is usually in the form of focused x-ray beams. It can also be in other forms such as electron beams, proton beams or gamma rays from radioactive sources.  Radiation therapy is a localised treatment, which means it generally affects only the area being treated. Treatment is carefully planned to do as little harm as possible to the normal body tissue near the cancer.

How does radiation therapy work

Radiation therapy aims to kill or damage cancer cells in the area being treated. Cancer cells begin to die days or weeks after treatment starts, and continue to die for weeks or months after it finishes. Although the radiation can also damage healthy cells, most of these cells tend to receive a lower dose and can usually repair themselves. Your should not feel any pain or heat during radiation therapy.

Many people will develop temporary side effects during or shortly after treatment that may cause pain or discomfort.

Why have radiation therapy

Research shows that about one in two people with cancer would benefit from radiation therapy. It can be used in three main ways:

  • As the main treatment to achieve remission or cure. Radiation therapy may be given with the aim of causing the cancer to reduce or disappear. This is called curative or definitive radiation therapy.Sometimes definitive radiation therapy is given with chemotherapy to increase its effectiveness. This is called chemoradiation or chemoradiotherapy.
  • To help other treatments achieve remission or a cure. Radiation therapy is often used before (neoadjuvant) or after (adjuvant) other treatments to make the treatment more effective.
  • For symptom relief. Radiation therapy can help to relieve pain and other symptoms by making the cancer smaller or stopping it from spreading. This is known as palliative treatment.

How is radiation therapy given

There are two main ways of giving radiation therapy, outside the body or inside the body. You may have one or both types of radiation therapy, depending on the cancer type and other factors.

How will I know the treatment has worked

Because cancer cells continue to die for weeks or months after treatment ends, your radiation oncologist most likely won’t be able to tell you straightaway how the cancer is responding. However, they can help you manage any side effects.

After treatment is finished, you will have regular check-ups. Your radiation oncologist will do a physical examination, and arrange tests or scans to check whether the cancer has responded to treatment. You may not know the full benefit of having radiation therapy for some months.

If radiation therapy is given as palliative treatment, the relief of symptoms is a good sign that the treatment has worked. This may take a few days or weeks.

What are the side effects

Radiation therapy can treat many cancers, but it can also injure healthy cells at or near the treatment area. This can lead to side effects. Some people experience many side effects, while others have very few or none. Many factors can affect the type and severity of side effects including; the part of the body treated; the type or radiation therapy; the dose of the radiation needed; any other treatments you might be having; and your general health.

Common side effects of radiation therapy may include:

  • Fatigue
  • Appetite loss
  • Skin problems
  • Hair loss
  • Nausea
  • Bladder problems
  • Bowel problems
  • Sexuality and intimacy issues
  • Infertility
  • Mouth and throat problems
  • Lymphoedema
  • Tissue hardening (fibrosis)


See our resources for more information on Radiation Therapy

If you are a patient, family or friend, and would like to order a copy of our Understanding Radiation Therapy booklet, please call Cancer Council 13 11 20.


The information available on this page should not be used as a substitute for advice from a properly qualified medical professional who can advise you about your own individual medical needs. It is not intended to constitute medical advice and is provided for general information purposes only. See our Disclaimer.