Radioactive iodine treatment for thyroid cancer
This page tells you about radioactive iodine treatment for thyroid cancer. There is information about
Radioactive iodine treatment for thyroid cancer
This type of radiotherapy for thyroid cancer is called internal radiotherapy. It uses a radioactive form of iodine called iodine 131 or I-131. The radioactive iodine circulates throughout your body in your bloodstream. Thyroid cancer cells will pick up the iodine wherever they are in your body. The radiation in the iodine will then kill the cancer cells.
This is a targeted treatment. It will not affect other body cells as it is only thyroid cells that pick up iodine. The treatment is only suitable for follicular thyroid cancer and papillary thyroid cancer. Even if you have one of these types of thyroid cancer, this treatment may not be suitable for you. Your doctor will carry out a test to see if your cancer cells pick up iodine or not.
Having the treatment
To have the treatment, you go into hospital for a few days. You have the iodine in a drink or capsule, or it can be injected it into a vein in your arm. You won’t be able to eat or drink for a couple of hours so your body can absorb the iodine. After that, you can eat normally. The treatment will make you slightly radioactive and you will stay in a single room for a few days. Then you will have a scan to see if the radiation has dropped to a safer level. Once it has, you will be able to go home.
You can view and print the quick guides for all the pages in the Treating thyroid cancer section.
Radioactive iodine treatment is a type of internal radiotherapy. The treatment uses a radioactive form of iodine called iodine 131 or I-131. The radioactive iodine circulates throughout your body in your bloodstream. Thyroid cancer cells pick up the iodine wherever they are in your body. The radiation in the iodine then kills the cancer cells.
This is a targeted treatment. It doesn't affect other body cells, because only thyroid cells take up the iodine. The treatment is only suitable for some types of thyroid cancer. It is used for
- Follicular thyroid cancer
- Papillary thyroid cancer
Even if you have one of these types of thyroid cancer, this treatment may not be suitable for you. You will be given a test dose to see if your cancer cells take up iodine, as not all of them do.
Radioactive iodine treatment is given
- After surgery, to kill any cancer cells left behind
- To treat thyroid cancer that has spread
- To treat thyroid cancer that has come back after it was first treated
Before you have radioactive iodine treatment, you may be given a manmade type of thyroid stimulating hormone called recombinant human TSH (rhTSH) for a few weeks beforehand. It helps any thyroid cancer cells in the body to take up radioactive iodine. Or, your doctor may ask you to stop taking your thyroid hormone tablets. This will be for 4 weeks if you are taking T4 (thyroxine) or 2 weeks if you are taking T3 (liothyronine). This is because the I-131 works best when the levels of another hormone called TSH (thyroid stimulating hormone) are high. The levels of this hormone in your blood start to rise as soon as you stop taking thyroid hormone tablets.
In some situations, your doctors may not ask you to take thyroid hormone tablets until after your surgery and radioactive iodine treatment have finished.
2 weeks before you have radioactive iodine treatment, you will be asked to start eating a low iodine diet. This is because too much iodine in your body can stop the treatment working so well. You should cut out any food coloured pink with the additive E127. So, do not eat
- Spam or salami
- Tinned strawberries
- Glace cherries
- Pink pastries or sweets (look on the labels for E127)
You should also not have
- Iodised table salt or sea salt
- Cough medicine
- Fish and seafood
- Vitamin supplements that say they contain iodine
Dairy products contain some iodine, so you need to cut down on eggs, cheese, milk and milk products. You don't have to cut these out altogether but have as little as you can.
To have radioactive iodine treatment, you go into hospital for a few days. You will be looked after in a single room. The treatment makes you slightly radioactive for a few days, so the time that the staff and your visitors spend with you will be limited to protect them. Your sweat and urine will be radioactive during this time. Your sheets may be changed every day and the hospital staff may ask you to flush the toilet more than once after you have used it.
You have the radioactive iodine as a drink or capsule. Or the iodine can be injected into a vein in your arm. Your nurse will ask you not to eat or drink for a couple of hours so that your body can absorb the iodine. After that, you can eat normally. You should try to drink a lot to flush the radioactive iodine out of your system.
You will have to stay in your single room for a few days until your radiation levels have fallen. A radiation monitor (Geiger counter) may be used to check your levels of radioactivity or test anything that is taken out of your room. You can bring videos, tapes and books in to keep you entertained. Anything taken out of the room will be monitored and some of your possessions may be kept on the ward for a couple of days if they show any radioactivity. After that time, they will be safe again and will be given back to you.
After a few days, you will have a scan to see if the radioactivity has dropped to a safe level. Once it has, you will be able to go home. You may be told that you shouldn't be in contact with children or breastfeeding mothers for a short time when you get home. Check this with the staff before you go, so that you're sure about what you can and can't do and how long you need to take precautions. If you had to stop taking your thyroid hormone tablets, your nurse will tell you when you can start to take them again. Usually, this is 3 days after your treatment.
Your doctors may ask you to have a radioactive iodine scan a few weeks after the treatment to see if it shows any thyroid cancer cells left in your body. If there are any cancer cells, you may have further doses of the radioactive iodine treatment.
If you plan to travel abroad you should be aware that you may set off radiation alarms at airports. This could happen up to 12 weeks after your treatment. Make sure you take a certificate from the hospital or a letter from your doctor telling which treatment you have had.
There is more about radioactive iodine treatment and the safety precautions in the radiotherapy section of CancerHelp UK.
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