Radioactive iodine treatment for thyroid cancer This information is an extract from the booklet, Understanding thyroid cancer. You may find the full booklet helpful. We can send you a copy free see page 5. Contents Radioactive iodine Preparing for radioactive iodine treatment Side effects Safety measures Fertility and breast feeding Radioactive iodine Radioactive iodine treatment is a type of internal radiotherapy. The radioactive substance used for treatment is the same as that used for a radioisotope scan that is used to diagnose thyroid cancer, but given in larger doses. Radioactive iodine treatment is mainly taken as capsules, but can be taken as a drink or injected into a vein in your arm (intravenously). It s a way of giving radiotherapy internally, rather than externally using high-energy rays. It s common for an operation for papillary or follicular thyroid cancer to be followed by treatment with radioactive iodine. The iodine treatment can destroy tiny amounts of normal thyroid tissue and any cancer cells that are sometimes left behind after an operation. The treatment is sometimes known as thyroid remnant ablation. Macmillan and Cancerbackup have merged. Together we provide free, high quality information for all. Questions about cancer? Ask Macmillan 0808 808 00 00 www.macmillan.org.uk Page 1 of 5
The treatment uses a radioactive iodine called iodine131. The thyroid cells absorb the iodine and receive a very high dose of radiation, which will help to destroy them and any cancer cells that might still remain. Radioactive iodine has very little effect on other parts of the body since other cells don t absorb iodine as much as the thyroid cells. Radioactive iodine treatment can be repeated if further tests show that thyroid cells are still present. Radioactive iodine treatment is only used to treat papillary or follicular thyroid cancer. However, it isn t suitable for all people with these types of thyroid cancer and you will be given a test dose to make sure that your thyroid cells absorb the iodine. Preparing for radioactive iodine treatment If you are taking thyroid hormones (T3 or T4) these are usually stopped for 2 4 weeks before the treatment. Most people find that stopping the hormone replacement therapy makes them feel very tired, but it s important that you do this or the radioactive iodine treatment won t work. To help overcome the potential problems of stopping your hormone replacement therapy, it may be possible to be treated with recombinant human thyroid stimulating hormone (rhtsh). This drug, also known as thyrotropin alfa (Thyrogen ), is given as two injections into a muscle, usually in the buttock. It allows you to carry on taking your hormone replacement tablets and avoid the symptoms of thyroid hormone withdrawal. Diet Before radioactive iodine treatment you may be asked to start eating a low iodine diet, as too much iodine in your body will make the treatment less effective. You ll be given advice about which foods to avoid, including the following: fish and seafood table salt that has had iodine added cough medicines Page 2 of 5 Questions about cancer? Ask Macmillan 0808 808 00 00 www.macmillan.org.uk
foods that contain the pink food colouring E127, such as salami, glacé cherries and tinned strawberries vitamin supplements that contain iodine. You should also try to cut down on the amount of dairy products that you eat, as these also contain some iodine. This includes foods such as: milk and products which contain milk eggs cheese. Side effects Unfortunately, unlike external radiotherapy, this treatment makes you slightly radioactive for about 4 5 days. During this time the radioactivity will be gradually lost from your body in your urine, bowel motions (stools), blood, saliva and sweat. This means that for a few days you ll need to be looked after in hospital until the radioactivity has reduced to a safe level. Very rarely, you may have pain or feel sick (nausea), tired and/ or breathless after having radioactive iodine treatment. If these side effects occur, let your nurse or doctor know, as medicines can be prescribed to help. A rare, long-term side effect of radioactive treatment is a dry mouth. This can happen if the radioactive iodine is absorbed by the salivary glands. Let your doctor know if you develop a dry mouth. Safety measures Because of the possibility of unnecessary radiation exposure to the hospital staff and your friends and relatives, certain safety measures are taken while the radioactive iodine is still in your body. The staff looking after you will explain these restrictions to you in detail before you start your treatment. Each hospital has different routines, and it s worth visiting beforehand to discuss the procedure with the nursing and medical staff. Questions about cancer? Ask Macmillan 0808 808 00 00 www.macmillan.org.uk Page 3 of 5
You may be admitted to the ward the day before your treatment so that the staff can go over the procedure with you. This is a good time to ask questions and it may help to make a list of them beforehand. What will happen You ll probably be in a side room, away from the main ward. You may have the room to yourself or be with someone else having similar treatment. Lead screens may be put on either side of your bed or in the doorway to block any radiation that is given out. Visitors will be restricted, and only allowed to stay in the room or sit at the end of the bed for a short time, if at all. They can talk to you from outside the room through an intercom. Children under 18 and women who are pregnant will not be allowed to visit. Staff and visitors will be asked to stand away from your bed to reduce their exposure to the rays. An instrument called a Geiger counter will be used to monitor the level of radiation in the room. The nurses may wear a small counter. You will probably be in the single room for a short time, sometimes only one or two days. You can bring books and magazines into your room, watch TV or listen to the radio or an MP3 player. You may not be able to take these things home for several weeks after you leave the hospital. These safety measures and visiting restrictions can make you feel very isolated, frightened and depressed at a time when you want people around you. If you have these feelings it s important to let the staff looking after you know. People are different in the way they handle their fears; some find it easier to know everything about their treatment, while others prefer to know as little as possible. If you want any explanations, the staff on the ward will be happy to help you. It often helps to bring your fears or worries into the open by talking to the staff or to family and friends. Page 4 of 5 Questions about cancer? Ask Macmillan 0808 808 00 00 www.macmillan.org.uk
Fertility and breast feeding You should not become pregnant, or father a child, while being treated for thyroid cancer, and for six months to a year afterwards. If you are pregnant, you can t be given radioactive iodine treatment. For this reason, you must tell your doctor if you are, or think you might be, pregnant. Your fertility shouldn t be affected by radioactive iodine treatment, although there is a very small risk if you need to have repeated treatments. Your doctor or nurse can give you more information and support about this. If you are breastfeeding, you must stop a couple of days before you are treated with radioactive iodine. Although it isn t safe to start breastfeeding again after your treatment, it will be safe for you to do so after future pregnancies. More information and support If you have any questions about cancer, ask Macmillan. If you need support, ask Macmillan. Or if you just want someone to talk to, ask Macmillan. Our cancer support specialists are here for everyone living with cancer, whatever you need. Call free on 0808 808 00 00, Monday Friday, 9am 8pm www.macmillan.org.uk We make every effort to ensure that the information we provide is accurate but it should not be relied upon to reflect the current state of medical research, which is constantly changing. If you are concerned about your health, you should consult your doctor. Macmillan cannot accept liability for any loss or damage resulting from any inaccuracy in this information or third party information such as information on websites to which we link. Macmillan Cancer Support 2010. Registered charity in England and Wales (261017), Scotland (SC039907) and the Isle of Man (604). Registered office 89 Albert Embankment, London, SE1 7UQ Questions about cancer? Ask Macmillan 0808 808 00 00 www.macmillan.org.uk Page 5 of 5