Series No 5 - Molecular Radiotherapy for adults having radioactive iodine (131I) treatment

We want to involve you in all the decisions about your care and treatment. If you decide to go ahead with treatment, by law, we must ask for your consent and will ask you to sign a consent form. This confirms that you agree to having the procedure and understand what it involves.   

Staff will explain all the risks, benefits and possible alternatives before they ask you to sign a consent form. If you are unsure about any aspect of your proposed treatment, please do not hesitate to speak to the team looking after you. 

Radioactive iodine (¹³¹I) is a form of radiotherapy treatment called molecular radiotherapy (MRT) that has been used to treat thyroid cancer for many years. It is a targeted method of destroying any remaining normal thyroid tissue or thyroid cancer cells that may remain following your total thyroidectomy surgery.

Your thyroid gland and related cells need iodine to work. They take up any iodine in the body. Radioactive iodine (¹³¹I) is a type of iodine that is radioactive. You usually have radioactive iodine as a capsule or a drink. The radioactive iodine from the drink or capsule is absorbed into your body and picked up by the thyroid cancer cells, even if they have spread to other parts of the body. The radiation then destroys the cancer cells. It is known as targeted radiotherapy because the treatment goes straight to the cancer cells and has very little effect on healthy cells in the body. 

Radioactive iodine (¹³¹I) treatment, together with surgery, will maximise the chances of eradicating your cancer. The need for treatment depends on the risk that your cancer might progress after surgery. It is not needed for very tiny cancers which have been removed. It is certainly needed in high-risk patients where the disease has spread. Some patients with low-risk disease may choose not to have this treatment. However, this is something that you should discuss with the clinical oncologist treating you before making a decision. 

At the first visit you will meet the consultant clinical oncologist who will talk to you about the plan for treatment and explain what to expect. You will have a chance to ask any questions you may have at this appointment.   

You will also meet the molecular radiotherapy team who will coordinate your care and treatment.

For a good uptake of radioactive iodine (¹³¹I), your blood levels of thyroid stimulating hormone (TSH) need to be high. To stimulate your levels of TSH, you will be required to stop certain medications or have injections to ensure the treatment is effective. The doctor will advise which method is best for you. 

Patients are given injections of rhTSH (thyrotropin alfa), also known by the trade name of Thyrogen®. These allow you to carry on taking your thyroid medication throughout treatment. They are given to you 48 and 24 hours before your treatment.

However, not all patients are suitable, or able to have Thyrogen® injections. If this is applicable to you, you will need to stop your Levothyroxine Sodium (T4) four weeks before admission or your Liothyronine (T3) ten days before admission. You may feel tired or weak when not taking the tablets. This is normal and the symptoms will disappear once you start taking the tablets again, which is normally on discharge from hospital.  

For two weeks before your admission you should avoid iodine-rich foods. Eating these foods may reduce the effectiveness of the treatment. We advise that you: 

• Do not eat fish, kelp, and all seafood. 
• Do not take vitamin supplements which contain iodine or cod liver oil. 
• Do not take cough medicine, iodised table salt or sea salt. 
• Do not eat foods artificially coloured pink or red such as canned and glacé cherries, canned strawberries, spam, and salami. These contain the colouring material E127 which is rich in iodine. 
• Certain CT scans use iodine-based contrast – if you are having a CT prior to treatment please inform your doctor or the molecular radiotherapy (MRT) radiographer booking your treatment.  If you have had a recent CT scan with iodine-based contrast your treatment will be delayed for three months. 

Please continue taking any other medications that you have been prescribed and bring a supply with you on admission and show them to the doctor who examines you.  

You should not have radioactive iodine (¹³¹I) treatment if you are pregnant or breastfeeding. You must tell the staff if there is any chance of you being pregnant. If you are of child-bearing age, you will need to have a pregnancy test prior to treatment. Treatment will only be given if you are not pregnant. 

All individuals with internal reproductive organs (a uterus) of child-bearing ability (12-55 years) will have a pregnancy test before treatment starts. Individuals should not become pregnant for at least six months after treatment. Individuals with external reproductive organs (testes) should not conceive a child for at least four months after treatment. All patients should use reliable contraception throughout this period. 

If you will be having multiple radioactive iodine (¹³¹I) treatments, there may be a small risk your fertility is affected in the future. Your medical team will discuss this with you if it is appropriate. Female fertility should not be affected in the long term even after repeated doses of radioactive iodine (¹³¹I) treatments. There may be a small risk of reduced male fertility if repeated radioactive iodine (¹³¹I) treatments are needed. In this situation you can be referred for sperm banking. The MRT radiographers will discuss any issues around sex, contraception, and intimacy with you. 

On the day of your admission to UCH, go directly to the ward where you will be having treatment. You will be shown to your room and have a blood test. You will stay in a protected side room with en-suite shower and toilet (Fig.1).

Before administration of the radioactive iodine, you will be given anti-sickness drugs to reduce the risk of feeling sick or being sick after treatment.  

The treatment is routinely given as a small capsule, and you will be given some water to help you swallow it. If you cannot swallow capsules, we would give the treatment in liquid form instead. Please let us know at the earliest opportunity if you are unable to swallow capsules, as they will take time to order. The capsule is given in the afternoon and the whole process takes only a few minutes.  

You will need to be an in-patient for three to five days. However, your stay may be longer, dependent on your family and home circumstances. During your admission you will have a whole-body scan in the nuclear medicine department. The scan produces a map to see where the iodine (¹³¹I) has been absorbed in your body.  

A porter will collect you from your room and take you directly to the nuclear medicine department for the scan. We ask that you take a shower prior to your scan and changes into fresh clothes and clean nonslip socks, or slippers should be put on when leaving the room, which will be provided by the team. 

You will also be monitored by the radiotherapy physics team throughout your stay on the ward. They will explain any restrictions you must follow. These restrictions will depend on the level of radiation in your body. They will also tell you when you can go home, assuming there are no medical reasons why you may need to stay in hospital for longer. 

The radioactive iodine (131I) treatment will enter your bloodstream and will be absorbed by any remaining thyroid tissue or thyroid cancer cells. Most of the remaining radioactive iodine (131I) will be excreted through your urine over the following days. It can also be excreted in other bodily fluids such as saliva, vomit, faeces, sweat, and oils secreted by your skin.   

The radiation from iodine (131I) is treating your cancer but it could be a risk to other people. You will therefore stay in a protected room to reduce any radiation exposure to other people.  

Strict regulations state that patients receiving radioactive drugs must stay in hospital until most of it has been excreted. Other rules are:

• You must not leave the room.  
• You must only use the shower and toilet in the en-suite 
• The en-suite shower and toilet cannot be used by anyone else.  
• You must only wash and dry your hands using the paper towels in the room and throw them in the yellow bin bags.  
• One of the two lead-lined doors to the suite must always be closed (Fig.2).   
• All medical and nursing staff and visitors entering the room must wear protective shoe covers, aprons, and gloves.  
• Anyone entering the room must wear a radiation monitor and record their measurements.  
• If you feel sick, please tell the nursing staff immediately. You can use the toilet in the en-suite to be sick in. The nurses can also provide a disposable bowl.   
• All patients are encouraged to sit rather than stand whilst urinating, to minimise the risk of contamination in the bathroom.  
• Please double flush the toilet.  

Please tell us if you have any accidents with bodily fluids while in hospital. It may be harmful to yourself and others if you fail to tell us.  

You will stay in the protected room most of the time during treatment. Exceptions include going to the nuclear medicine department for scans or in a medical emergency.   

You can wear hospital nightclothes and a dressing gown during your stay. If you wish to wear your own clothes, old and comfortable clothes are best to wear while you are admitted to hospital, so they can be disposed of.   

You should only bring items you will not need to take home immediately. This is because any personal possessions brought in will become contaminated with radiation. You may need to leave some things behind if they carry traces of radioactivity. The radiotherapy physics team will monitor the radiation levels of your belongings and let you know if there are any items they need to store. These items may need to be kept for up to three months. If you would like them back, please let us know and we can contact you when they are ready to be collected   

Meals will be brought to you three times a day. Meals will be served on paper plates with plastic cutlery for easy disposal. If you do not get a meal, please let a nurse know. Please let us know if you have any special dietary needs.  

There is a smart TV, books, mood lighting, a kettle, fridge, and an X-box in the room. If you are uncertain on what things you can bring in due to the risk of radiation contamination, please ask the MRT radiographers.

Adult visitors, who are not pregnant, should keep visits to a minimum (no more than five minutes per day) and sit outside the protected room behind a lead screen. All visitors must report to the nurse’s station on arrival.  

People under 18, pregnant or breastfeeding cannot visit under any circumstances.

We try to limit the number of times we change the bed linen while you are having treatment, to reduce the amount of radioactive waste. If the linen is visibly soiled, the nurses will give you fresh linen. 

All waste needs to be kept in the patient room and will be monitored by physics before being taken away. If waste begins to build up in the room, please let the nurses know.

You should plan for you to be in hospital for three to five days, although a longer stay is sometimes necessary. The radiotherapy physics team will give you a yellow card on discharge. The card has details of your treatment, any restrictions in place at the time your discharge, the time the restrictions are applied until and the contact details for the radiotherapy physics department.   

You should always carry this card with you after leaving hospital, until the date indicated on the card. If you are attending another healthcare setting during the restriction period, the yellow card must be shown to staff. The card will not prevent you from receiving treatment in an emergency, but it will allow the team to request information and advice from UCH. 

Depending on your radiation levels, you may need to avoid being in close contact with people for prolonged periods e.g., sharing a bed, particularly with children and pregnant individuals.   

You should not fly until they have reached a low radiation level which is determined by the radiotherapy medical physics team. It may take several days to reach this level.  

If you wish for your restrictions to be lifted earlier, we may recommend that you return to the hospital to be re-monitored. The radiotherapy physics team will discuss this with you before you are discharged from the ward. If you live some distance from UCH, it may be possible for re-monitoring to take place at a local hospital, with nuclear medicine facilities, with prior arrangement.

Usually there are no major side effects from the treatment. You may experience some discomfort in your salivary glands, soreness in the neck, dryness and discomfort in the mouth and/or swelling of your neck and salivary glands. Some patients may also experience an altered taste sensation. If you do experience these side effects, they should last no longer than a few days and simple analgesia can relieve your discomfort. Keeping hydrating throughout and after treatment can also help with side effects, as can chewing gum or sucking boiled sweets.  

Late side effects incurred by treatment can appear to develop months or years after radioactive iodine (¹³¹I) treatment. There is a very low risk of secondary malignancy and an increased risk of leukaemia in 0-5% of patients. This risk can increase with cumulative doses of radioactive iodine (¹³¹I) treatment and with the use of additional external beam radiotherapy.  

Patients who have had multiple radioactive iodine (¹³¹I) treatments may also be at an increased risk of developing secondary solid malignancies. Your Clinical Oncologist will discuss this with you in more detail at the time of consent. 

If you received Thyrogen® injections, you will continue with your thyroid hormone tablets throughout treatment. If you stopped taking your thyroid hormones, you will be given thyroid hormone replacement tablets to re-start after the treatment.  

You will be given an appointment to see your doctor in clinic approximately four weeks post-treatment. Your doctor will have all the results of your blood tests and post-treatment nuclear medicine scan and will discuss the results with you.

The treatment works slowly over a period of months. You will have an ultrasound scan and a blood test nine-twelve months after treatment. You may also require a diagnostic radioiodine whole body scan.  

Some patients may need more than one treatment. The post-treatment scan and blood tests are used to decide if any more radioactive iodine (¹³¹I) treatment is needed.

Radiation – The shortened term for ‘ionising radiation’. It is used to describe the wave or particle emitted by a substance.  

Radioactive – A term used to describe a substance that emits radiation.  Radioiodine (I-131) is radioactive. 

Radioisotope – A radioactive substance. For example, Iodine-131 is a radioisotope. 

Half-life – As radioisotopes emit radiation they decay and become weaker. The half-life is the amount of time it takes for a radioisotope to decay to a state in which it emits only half as much radiation. The half-life for radioiodine is eight days. 

µSv (microsievert) – A unit of radiation dose. 

Bq (Bequerel) – A unit which describes how much radioactivity is present. 

Dosemeter – A small device that is worn to measure radiation dose.  

Radiation meter – An electronic device used to detect the presence of radiation and measure radiation levels.   

Contamination – The presence of a radioisotope in an area it is not planned for it to be in. For example, the presence of a radioactive substance anywhere but in your body or in the toilet. 

Lead shield – Used to stop radiation. Since lead shields are very thick and lead is a very dense material, it stops or “absorbs” almost all of the radiation. 

Ablation – The destruction of residual thyroid tissue. ¹³¹I is preferentially taken up by any thyroid tissue and destroys it with radiation. 

Thyroid Stimulating Hormone – This is released by the pituitary gland to regulate the function of the thyroid. Thyroid replacement hormones, such as Levothyroxine Sodium (T4) and Liothyronine (T3), suppress TSH levels following removal of the thyroid. However, high TSH levels promote high uptake of ¹³¹I which is why replacement hormones are stopped pre-treatment.

Molecular Radiotherapy Team

020 3447 4286

020 3456 7890 bleep 1089 or 1097

uclh.RadiotherapyIsotopes@nhs.net

Molecular Radiotherapy Pathway Coordinator

020 3447 7283

T11 North

020 3447 1102/020 3447 118

Radiotherapy Medical Physics

020 3456 7890 Bleep 2173

If you have any concerns that you would like to discuss in confidence, please contact our PALS (Patient Advice and Liaison Service) for information and advice. 

020 3447 3042

uclh.pals@nhs.net

British Thyroid Foundation 

0142 381 0093  

Butterfly Thyroid Cancer Trust

0120 754 5469 

enquiries@butterfly.org.uk  

British Thyroid Association

Young Lives vs Cancer (formerly CLIC Sargent)

0300 330 0803  

Macmillan Cancer Support

0808 808 0000  

cancerline@macmillan.org.uk   

Cancer Research UK

0808 800 4040    

Carers UK

0808 808 7777  

adviceline@carersuk.org   

NHS Choices

UCLH cannot accept responsibility for information provided by other organisations.