About radiation therapy

Radiation therapy uses a controlled dose of radiation to kill cancer cells or damage them so they cannot grow, multiply or spread. Most forms of radiation therapy use focused, high-energy x-ray beams (also known as photons). Radiation can also be electron beams, proton beams, or gamma rays from radioactive sources. Radiation therapy is a localised treatment. This means it generally affects only the area being treated.

When is radiation therapy used?

It is estimated that radiation therapy would be a suitable part of treatment for 1 in 2 people with cancer. The Guides to Best Cancer Care set out the recommended treatment pathways in Australia for many types of cancer. For some cancers, radiation therapy is recommended as the most effective approach, either on its own or in combination with other treatments. For other cancers, other treatments may be more effective. For more on this, see cancer.org.au/cancercareguides.

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. Treatment is carefully planned to do as little harm as possible to healthy cells near the cancer. Most of these cells receive a lower dose and can usually repair themselves.

Why have radiation therapy?

Radiation therapy can be used for different reasons:

To achieve remission or cure – Radiation therapy may be given as the main treatment to make the cancer reduce or disappear. This is known as curative or definitive radiation therapy. Sometimes definitive radiation therapy is given together with chemotherapy to make it work better. This is called chemoradiation.

To help other treatments – Radiation therapy is often used before or after other treatments. If used before (neoadjuvant therapy), the aim is to shrink a tumour. If used after (adjuvant therapy), the aim is to kill any remaining cancer cells.

To relieve symptoms – Radiation therapy may be used to make the cancer smaller or stop it spreading. This is known as palliative radiation therapy. It can help relieve pain and other symptoms.

Will I have side effects?

If radiation therapy injures healthy cells near the treatment area, side effects may occur. The side effects you have will vary depending on the part of the body treated, the dose of radiation and the length of treatment. Most side effects are temporary and tend to improve gradually in the weeks after treatment ends. For more on this, see Managing side effects.

How is radiation therapy given?

There are 2 main ways of giving radiation therapy – from 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.

External beam radiation therapy (EBRT) – The process is similar to having an x-ray. You will lie on a treatment table underneath a large machine that moves around your body. Radiation beams from the machine are precisely aimed at the area of the body where the cancer is located. The beam operates for a few minutes only. You won’t see or feel the radiation, although the machine can make noise as it moves. For more information, see EBRT.

Internal radiation therapy – A radiation source is placed inside the body or, more rarely, injected into a vein or swallowed. The most common form of internal radiation therapy is brachytherapy, where temporary or permanent radiation sources are placed inside the body next to or inside the cancer. For more information, see Brachytherapy.

→ READ MORE: Common questions about radiation therapy

Video: What is radiation therapy?

Watch this short video to learn more about radiation therapy (also known as radiotherapy).