Radiotherapy for thyroid cancer

This type of treatment is used less commonly than internal radiotherapy| for treating thyroid cancer. It is more commonly used to treat medullary or anaplastic thyroid cancer|, as they don’t respond to radioactive iodine treatment. Sometimes, both radioactive iodine and external radiotherapy will be used.

External radiotherapy may be given to treat medullary and anaplastic thyroid cancer:

• after surgery to destroy any cancer cells in the neck that weren’t removed by the operation
• if an operation to remove the thyroid can’t be done
• if the cancer comes back after treatment.

This treatment is given in the hospital radiotherapy department. The course is usually given every week day, with a rest at the weekend. The length of your treatment will depend on the type and size of the cancer. Your doctor will discuss your treatment with you in more detail beforehand. 

Planning your treatment Back to top

To ensure that the radiotherapy is as effective as possible, it has to be carefully planned by a clinical oncologist. This is a very precise treatment and it’s important that you’re able to lie still, in exactly the same position, for each treatment.

To help you do this, you may need to wear a see-through Perspex or plastic device called a ‘mask’, ‘mould’ or ‘shell’ that helps to keep your head and neck as still as possible. The mould allows you to see and breathe normally, but it may make some people feel claustrophobic. You will only have the mould on for a few minutes at a time, and most people soon get used to wearing it.

Your mould will be made on one of your first visits to the radiotherapy department. The radiographer (the person who gives the treatment) or the mould room technician will explain the whole process to you before starting. Our section on radiotherapy masks| explains more about how they're made.

Treatment planning is a very important part of radiotherapy and several visits may be needed. On your first visit to the radiotherapy department, you’ll have a CT (computerised tomography) scan taken of the area to be treated. A CT scan takes a series of x-rays which build up a three dimensional picture of the area. At the same time therapy radiographers will take measurements from you which are needed for treatment planning. This session will usually take about 45-60 minutes and you will need to wear your radiotherapy mask.

Sometimes you may also need to go to the hospital’s scanning department to have an MRI scan. This uses powerful magnetic fields to give a detailed picture of part of your body, which can give additional useful information.

The radiographer’s measurements and the information from the scans are fed into the radiotherapy planning computer to help your doctors plan your treatment more precisely.

Marks are drawn on the mask (or sometimes on your skin) to help the radiographer position you accurately, and to show where the rays are to be directed. If the marks are on your skin they must stay there throughout your treatment, but they can be washed off once your course of treatment is finished.

Sometimes a few small permanent marks (tattoos) may be made on your skin instead of pen marks. The marks are tiny and will only be done with your permission.

At the beginning of your treatment you’ll be given instructions on how to look after the skin in the area being treated.

During the treatment Back to top

The radiographer will position you carefully on the couch, with the mask fitted, and make sure you are comfortable. During your treatment, which only takes a few minutes, you will be left alone in the room, but you can talk via an intercom to the radiographer who will watch you from the next room.

Radiotherapy isn’t painful but you do have to lie still while your treatment is being given.

You may find it helpful to read our section on radiotherapy|, which discusses this treatment and the possible side effects in detail. 

Side effects Back to top

Radiotherapy can cause general side effects such as tiredness and it’s important to try to get as much rest as you can, especially if you have to travel a long way for treatment every day. We  have a section on coping with cancer-related tiredness (fatigue).|

Radiotherapy to the neck can also cause specific side effects such as:

• pain on swallowing
• a dry mouth
• taste changes
• darker, or red, sore skin.

These side effects vary depending on the dose of the radiotherapy and the length of your treatment. Your doctor or radiotherapist will discuss any possible side effects with you before you start your treatment. If your throat is sore and you find it painful to eat your normal diet, you can replace meals with nutritious, high-calorie drinks, which are available from most chemists. Our section on diet and cancer| has some helpful hints on how to eat when you’re feeling ill or when you find swallowing difficult.

Your radiographer will give you advice on how to care for the skin on your neck if it becomes sore. It’s best to avoid perfumed soaps or creams on this area and to keep the skin as dry as possible during your course of treatment. Use water to wash the skin and then gently pat it dry.

The side effects should begin to lessen gradually about three to four weeks after your treatment is over. It’s important to let your doctor know if they continue for longer than this. External radiotherapy doesn’t make you radioactive and it’s perfectly safe for you to be with other people, including children, throughout your treatment.

Your ability to become pregnant or father children isn’t affected by external radiotherapy treatment for thyroid cancer, but you’ll probably be advised to wait for at least a year. Women who become pregnant will have their hormone levels carefully monitored throughout the pregnancy.