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. Radiation can also be 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.

Learn more about:

• Why have radiation therapy?
• How does radiation therapy work?
• How is radiation therapy given?
• What is chemoradiation?
• Radiation therapy for children
• Video: What is radiation therapy?

Why have radiation therapy?

Radiation therapy is an important part of treating cancer. It’s estimated that radiation therapy would be a suitable treatment for 50% of people with cancer.

It can be used in three main ways:

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

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

To relieve symptoms – 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 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 tend to receive a lower dose and can usually repair themselves.

Many people will develop temporary side effects during or shortly after treatment that may cause pain or discomfort. Read about ways to prevent or manage side effects.

How is radiation therapy given?

There are two 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) – Radiation beams from a large machine called a linear accelerator are precisely aimed at the area of the body where the cancer is located. The process is similar to having an x-ray. You will lie on a treatment table underneath a machine that moves around your body. You won’t see or feel the radiation, although the machine can make noise as it moves.

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.

What is chemoradiation?

Chemoradiation means having radiation therapy at the same time as chemotherapy. The chemotherapy drugs make the cancer cells more sensitive to radiation therapy. Having radiation therapy and chemotherapy together increases the success of the treatment compared with having either treatment on its own.

Chemoradiation is only used to treat some cancers such as anal, brain, bowel, head and neck, lung, cervical, uterine, oesophageal, pancreatic and vaginal cancer.

If you have chemoradiation, you will usually receive chemotherapy a few hours before some radiation therapy appointments. Your doctor will talk to you about your treatment plan.

The side effects of chemoradiation depend on the type of chemotherapy you have. They also depend on the radiation therapy treatment area.

Your radiation therapy team can provide support and information about how to manage any side affects you develop.

Video: What is radiation therapy?

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