Radiotherapy for thyroid cancer

External beam radiotherapy is used to treat some types of thyroid cancer. Find out how it works and learn some of the side effects.

About external beam radiotherapy for thyroid cancer

External beam radiotherapy is used in different ways depending on the type of thyroid cancer.

  • Follicular and papillary thyroid cancer

    Radiotherapy may be used for follicular and papillary thyroid cancer if it is not possible to remove all of the tumour with surgery. Or if the cancer has spread to other parts of your body, for example the bones.

  • Medullary thyroid cancer

    Radiotherapy may be used for people with medullary thyroid cancer who have a high risk of cancer coming back in the neck after surgery. Or if some parts of the cancer could not be removed with surgery, or if it has spread to other parts of the body.

  • Anaplastic thyroid cancer

    People with anaplastic thyroid cancer may have radiotherapy as their main treatment. It is sometimes given with chemotherapy. This is called chemoradiation.

External beam radiotherapy does not make you radioactive. It is safe for you to be with other people, including children, throughout your treatment.

Planning your treatment

Before you start your treatment, it needs to be carefully planned. Planning makes sure that the radiotherapy is aimed precisely at the cancer. This means it causes the least possible damage to the surrounding healthy tissue.

If your neck area is being treated, you will need to have a mould or mask made before your treatment is planned. This is to keep your head still while you have treatment. You will also have a CT scan to help with planning.

Side effects of radiotherapy for thyroid cancer

Radiotherapy can cause general side effects such as tiredness (fatigue).

Side effects of radiotherapy to the neck can include:

Your doctor, specialist nurse or radiotherapist will discuss any possible side effects with you before you start your treatment. They can also give you information to help you cope with any side effects.

Support from Macmillan

Macmillan is here to support you. If you would like to talk, you can do the following:

  • Call the Macmillan Support Line on 0808 808 00 00.
  • Chat to our specialists online.
  • Visit our radiotherapy and side effects forum to talk with people who have been affected by radiotherapy, share your experience, and ask an expert your questions.

About our information

  • References

    Below is a sample of the sources used in our thyroid cancer information. If you would like more information about the sources we use, please contact us at

    British Medical Journal. Best Practice Guidelines, Thyroid cancer. 2020.

    European Society Medical Oncology (ESMO): Thyroid cancer, Clinical Practice Guidelines for Diagnosis, Treatment and Follow-up. 2019.

    National Institute for Health and Care Excellence (NICE). TA535: Lenvatinib and Sorafenib for treating differentiated thyroid cancer after radioactive iodine. 2018. [accessed May 2021].

  • Reviewers

    This information has been written, revised and edited by Macmillan Cancer Support’s Cancer Information Development team. It has been reviewed by expert medical and health professionals and people living with cancer. It has been approved by Senior Medical Editor, Professor Nick Reed, Consultant Clinical Oncologist.

    Our cancer information has been awarded the PIF TICK. Created by the Patient Information Forum, this quality mark shows we meet PIF’s 10 criteria for trustworthy health information.

The language we use

We want everyone affected by cancer to feel our information is written for them.

We want our information to be as clear as possible. To do this, we try to:

  • use plain English
  • explain medical words
  • use short sentences
  • use illustrations to explain text
  • structure the information clearly
  • make sure important points are clear.

We use gender-inclusive language and talk to our readers as ‘you’ so that everyone feels included. Where clinically necessary we use the terms ‘men’ and ‘women’ or ‘male’ and ‘female’. For example, we do so when talking about parts of the body or mentioning statistics or research about who is affected.

You can read more about how we produce our information here.

Date reviewed

Reviewed: 01 June 2021
Next review: 01 June 2024
Trusted Information Creator - Patient Information Forum
Trusted Information Creator - Patient Information Forum

Our cancer information meets the PIF TICK quality mark.

This means it is easy to use, up-to-date and based on the latest evidence. Learn more about how we produce our information.