Patients & Families

About Radiotherapy

The following content contains images and descriptions of cancer treatment that some people may find upsetting or triggering.

Radiotherapy is a common treatment for cancer. Around half of people with cancer need it to help them. There are different types of radiotherapy. Radiotherapy can cause side effects and late side effects. When patients understand these side effects, they can feel more prepared for treatment and life after treatment. 

Radiotherapy uses radiation to destroy the DNA of cancer cells. The treatment can work well alongside other treatments. It is common for a patient to have several treatments. 

These can include:

  • Radiotherapy
  • Chemotherapy
  • Surgery
  • Immunotherapy
  • Endocrine therapy

Some patients are only treated with radiotherapy, because of the nature of their cancer.

What can Radiotherapy do?

Radiotherapy is a proven treatment for cancer. Radiotherapy can:

  • Remove signs of the disease
  • Reduce the chances of cancer coming back 
  • Reduce the symptoms of cancer, so the patient feels better and has a better quality of life
  • Cause side effects 

Types of radiotherapy

Radiotherapy can be given from outside the body

  • This is called external radiotherapy

Radiotherapy can be given from inside the body too

  • This is called internal radiotherapy

The most common form of radiotherapy is external beam radiotherapy. This is where a machine aims a source of high energy radiation at the cancerous cells. The radiation travels through the patient’s body to the area of cancer.

Internal radiotherapy is where the radioactive source is put inside the body. This can be where a radioactive object is placed in, or close to, the tumour. Or when a radioactive liquid is absorbed by the cancer cells.

How well does radiotherapy work?

Radiotherapy is good at treating common cancers. It can be used before or after surgery. 

Radiotherapy can also be the main treatment used for certain cancers.  

Sometimes it is better for a patient to only have radiotherapy. This is because surgery can come with risks, and it can sometimes be safer not to operate.

If a patient’s cancer is no longer curable, radiotherapy can still help. It does this by removing some of the pain and problems that cancer causes. 

For example, pain in the bones from the spread of cancer can be improved (60%) or even completely removed (25%) for patients (1). 

New technology in radiotherapy has made life better for many cancer patients. Treatments have become quicker, more accurate, and more effective.  

How does radiotherapy work?

Radiotherapy works by destroying cancer cells in the area that is being treated. It damages the DNA inside cancer cells. This stops the cancer cells growing, repairing and multiplying. Radiotherapy can also change healthy cells. This can cause side effects and late side effects. But remember:

  • Healthy cells recover from treatment better than cancer cells
  • Treatment teams work hard to reduce the effect on healthy cells as much as possible

Understanding side effects

Radiotherapy can cause side effects and late side effects. It is important that every cancer patient understands what these might be and when they might happen.

We have created a special section on our website where patients can learn more about side effects. 

We encourage patients to speak to their team about side effects and ask lots of questions. 

  1. The Challenges of Managing Bone Pain in Cancer – PMC (
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