What is the role of Radioactive Iodine and External Beam Therapy in Papillary Cancer of the Thyroid?

It is very difficult to remove all the thyroid tissue when performing a "total thyroidectomy". Radioactive iodine is used to destroy any missed normal thyroid tissue in the neck or malignant thyroid tissue that was not removable.Radioactive iodine works because normal thyroid tissue concentrates iodine from the blood stream.In addition under the influence of high TSH levels,malignant thyroid tissue usually takes up iodine in significant amounts.This phenomenon allows the residual thyroid tissue to receive a large targeted dose of radiation with little damage to the surrounding structures.

Radioactive iodine is used in three separate situations:

#1.After Surgery to destroy any residual thyroid cancer cells or residual normal thyroid tissue.

#2.To treat thyroid cancer that has spread to the lymph nodes,lungs or bones.

#3.To treat thyroid cancer that has come back after initial treatment by surgery or previous radioactive iodine or both.

Prior to treatment the blood TSH must be grossly elevated and this may be done in two ways. The traditional method is to stop thyroid medication (T3 or T4) until the TSH is grossly elevated. This takes 3-4 weeks in the case of T4 and2 weeks in the case of T3.Without thyroxine one feels very weak and as a result T3 replacement is preferred.To avoid this problem there is now a method of giving intramuscular recombinant TSH (rhTSH),which allows the patient to continue thyroxine still allowing an effective uptake of radioactive iodine by thyroid tissue.

The low iodine diet/ low iodide Diet

Four weeks prior to radioactive iodine therapy patients should avoid foods and medications with a high iodine content, these include.

#1.Milk and milk products :-all dairy products are rich in iodine.Please limit milk to 125mls(1/2cup) per day or instead 30 grams(1 once) of cheese.

#2. Fish and seafood :-Please avoid all seafood and saltwater fish.One can eat freshwater fish once a week.

#3.Meat and Poultry :- Limit meat or poultry to 125grams(5 onces) cooked weight per day

#4.Eggs:- limit to three per week

#5. Grain and Cereals:- Limit to twice a week. Fortunately white bread and white rolls have a low iodine content and can be eaten freely.

#6.Vegetables:-Avoid kelp,broccoli,spinach.One small potato may be eaten daily. All other vegetables may be eaten in normal quantities.

#7. Iodized table salt must not be used.

#8.If you are on medications please discuss with your doctor or pharmacist their possible iodine content.

#9.Avoid any food coloured with the additive E127.This incudes spam,salami,tinned strawberries,glace cherries and pink pastries and sweets.

#10.Certain CT scans use iodine contrast -if you are having a CT prior to your therapy please tell the radiographer so they do not use contrast.The contrast used for MRI scans does not interfere with your therapy and is safe to use.


Although it does not involve surgery, radioactive iodine treatment is often the most tiresome part of the treatment.If exogenous TSH is not used T4 or T3 must be stopped with its inevitable fatigue.The treatment entails isolation in a special room for up to five days.The protocols of management vary between medical centres but iodine containing foods and drugs must be avoided as indicated above.The main problem in hospital is boredom.

The HiLo Radioactive Iodine Trial

Some 20hospitalsin the UK are participating in a multicentre randomised trial of of high versus low dose radioiodine,with or without recombinant human thyroid stimulating hormone.The aim of this trial is to discover if a low dose of radioactive iodine(1.1GBq) is as effective as a high dose (3.7GBq)in ablating thyroid remnants and if using recombinant human thyroid stimulating hormone is as effective as withdrawal of thyroxine.This trial is known as the HiLo trial.The trial is being funded Cancer Research UK.Physicains in the UK are encouraged to be involved in this trial and if you need moreinformation please contact Pablo Alvarez the trial co-ordinator( This e-mail address is being protected from spambots. You need JavaScript enabled to view it ). An exellent review of the HiLo trialby three distinguished thyroid oncologists Drs U Mallick,C Harmer andA Hackshaw is in Clinical Oncology (2008)20:325-326.

When the results of the HiLo trial are available they will be used to formulate national and international guidelines.The results may well result the use of a low dose of radioactive iodinewith highcure rates withanda reduction in complication as compared to the high dose. There is one randomised study that suggests that a low dose is not as effective as a high dose. This study has been criticised because of its methodology.A non randomised study suggests that the low dose is as effective as the high dose but not being randomised has inherent problems.It is difficult for patients to know what to do when they are offered a place in trials! As regards the HiLo trial all the treatment arms are safe and not entering the trial never has any bearing on the patients overall management.Patients most feel comfortable with their decision which should be totallyrepected by their doctor.

Mr Lynn has strong views on the TSH level at the time of radioactive ablation.If the TSH is less than 30 Iu/l the the ablation should be delayed or two intramuscular injections of recombinant TSH given.Radioactive iodine with a low TSH is a waste of time and not effective!

All females of child bearing age should were appropriate should have a pregancy test prior to radioactive iodine therapy.Radioactive iodine is contraindicated in pregnancy.

There are in fact few immediate complications although there is sometimes tenderness in the neck,or the parotids (mumps glands).Rarely is this severe and it usually responds well to a short course of steroids.Later problems may include blockage of the parotid ducts with a mildly swollen face at meal times, which is usually self-limiting.There is no evidence that radioactive iodine treatment reduces fertility in the male or female.It is considered good practice for females not to become pregnant until at least 6 months after treatment.Males should follow the same rule delaying pregnancy in their partners for six months.

Follow up consists of regular thyroglobulin measurement with ultrasound of the neck. If there is proven recurrence further doses of radioactive are appropriate.


The use of external beam therapy (EBRT) in papillary thyroid cancer is usually limited to cases of unresected tumour in the neck.The results of treatment are often excellent.

The data on external beam radiation is controversial. Conventional EBRT most likely gives an inadequate radiation dose to the tumour bed or remnant. Intensity-modulated radiotheraphy (IMRT) allows the tumour to be treated reducing the risk of damage to the spinal cord.Its use is still subject to evaluation.

Mr Lynn has worked for many years with Dr Christopher Nutting the specialist head and neck Oncologist -his website is www.chrisnutting-oncology.co.uk

A Patient Account of Radioactive Iodine Therapy following Thyroid Surgery.

(This is an unsolicited and unedited account of Shiela Cornhill - a patient who underwent radioactive iodine treatment at Charing Cross Hospital. Mr Lynn is very grateful for her contribution and has attempted to implement her very thoughtful suggestions.)

In Solitary

(A personal account of my experiences of the subsequent radium treatment after undergoing surgery for the removal of my thyroid gland).

I felt privileged to have my operation carried out by Mr Lynn. I also felt very reassured after visiting his Web Site before entering the hospital.
From a patient's point of view, the operation to remove the thyroid gland is straight forward hospital surgery. Stringent tests are made before the surgical procedure and once the operation has been performed, the recovery time is short. I was allowed home 3 days later. No pain, only a little discomfort from the stitches which were removed a fortnight later.


"Your operation was successful and now we propose to give you some radiation treatment to clear up any cancerous cells that we may have missed".
In my mind I visualised being wheeled into some kind of machine that enveloped me and shot radioactive darts at my body. Or perhaps they stuck radium needles into the affected parts. I had to know. "What is this treatment and how will it affect me?" I asked. I was then told that I would have to go into hospital for about five days. A radioactive capsule would be administered, and I would have to stay in isolation for however long it took to flush the radioactivity out of my system. I would be in a lead protected room for my stay. "How will my system be flushed, through the veins or the stomach?" Unfortunately the young doctor was ill informed about this for she told me it would be through the veins. Thus I had visions of being attached to one of those hospital cranes that you wheel around with your drip bag hanging on it.
"Will I be sick and lose my hair?" "No it shouldn't affect you adversely at all". That was reassuring but I started to have nightmares about swallowing this capsule they spoke of. I have difficulty swallowing aspirin.
Treatment day came and I arrived at the hospital at 8am. I was told to sit in the day room until my room had been prepared for me. I was surprised to find myself on a ward that was identical to the surgical ward that I had been on just a few weeks previously. (I think I was expecting rows of lead-lined cubicles). In fact I was placed in a side ward that duplicated the original one, with it's own toilet and washroom. The only difference was the plastic. Plastic everywhere! The thick plastic that builders use to keep the brick dust off your carpets. The floor was covered, the chair, the side-cupboard, the light switches, the taps, phone, TV controls, everything except the bed and the toilet seat. A lead screen about four foot high, was wheeled in a placed just inside the door. I removed my shoes, coat and jumper and they were stored in a cupboard inside the doorway, on the other side of the screen.
When the preliminary blood tests etc. had been taken the fun began. A white coated doctor came as far as the screen and announced that he would be back with my capsule in a few moments. He came back to the doorway, covered his shoes with what I can only describe as blue plastic shower caps, put on his rubber gloves and stepped over an invisible line into my room. The capsule was quite small, much to my relief. It was in a gel like substance in a small pot. The doctor picked it up with a short plastic tube and rolled it into my mouth. That was all there was to it. There was no burning sensation or anything else. " I will be back later to take some measurements" said the doctor as he stood at the screen and removed one shoe cover, carefully placing that foot over the line, he then removed the other one and the gloves and threw them back into the room. "Would you put those in the bin please" he said as he departed.
This was it, my home for the next five days. The ward was on the eighth floor and I had a large window that looked out on the rear of the hospital complex. Beyond that was a cemetery, cheery view I thought.
I soon discovered that the nursing staff were not too keen on visiting me. I was required to drink as much water as I could manage. When I could attract a nurse or orderlies attention and ask for another supply, I had to stand at the screen and hold out my jug like a beggar, whilst some brave nurse leant in and filled it. Food was delivered in the same fashion. It came on disposable dishes and cutlery, which I then disposed of in the bin. On the second day I realised the bin had not been emptied before I took over residence. It started to 'hum'. The Ward Sister came with a replacement bag but said she couldn't remove the smelly one. That was tied up and deposited in the washroom. I washed up my dishes before I placed them in the bin, the previous tenant obviously didn't.
The doctor came to my room each day to take his measurements. It was my daily treat to watch his performance. He struck me as being like the absent-minded professor. He would go through his routine with the shoe covers and gloves just to tell me he would be coming in a few moments to measure me. Out he would go, balancing carefully on one foot as he stripped the other shoe cover and stepped out into the safe zone, leaving his little pile of gloves etc. on my floor. He was just as likely to go through this routine several times when he forgot to bring his papers or equipment with him.
He had an ordinary steel rule, one end of which he asked me to hold to my throat. At about a metre away he placed his Geiger counter on the rule and took a reading. This he recorded, waited about a minute then repeated the process. The first day he did this at least a dozen times and then told me I could have visitors but they could only stay for five minutes. No children or pregnant women and they could only speak to me from the doorway. I had previously told my family that I didn't want visitors so that didn't worry me.

I had taken books, some knitting and a small jig-saw in with me and was very glad of them, especially the jig-saw. They helped the time pass. There was a TV in the room but it was very loud and I couldn't adjust it. The rest of the wards seemed so quiet that it embarrassed me to have it on for long. I didn't want to disturb anyone.
The majority of hospitals seem to have bedside telephones now. This being the case you would be well advised to purchase a voucher card before entering your ward. This way you at least have contact with friends and relatives during your stay. I would warn you though, the phone charges are high, therefore £5 is about the least you should buy. Nominate someone before you leave home to be your intermediary. Phone them as soon as you know your bedside number, and get them to pass the number on to your contacts, that way they can phone you. (Costs them about 30p a minute I believe.)

By the fourth day I had done so well, drinking like a fish, that I had reduced my measurements sufficiently to be allowed home as long as I was picked up. I couldn't use public transport. My son Jamie volunteered to come for me. "Don't forget to bring me some trousers will you". I was not allowed to leave the hospital in the garments that I had been wearing and although I had brought spare tops and jumpers I only had the one pair of track suit bottoms which I had on.
Jamie arrived with my garment and I dressed straight away. The 'professor' gave me a plastic bag to carry my 'Hot' stuff in. "They must be washed three times" he said. "Leave me your wash-bag with tooth brush, toothpaste flannel etc, as I have to check them for radiation". Jamie and I sat in the day room whilst my belongings were checked out. We were called back to the ward where the contents of my wash bag were laid out on my bed which I had been in contact with for most of my stay.
"This is 'hot' the doctor said indicating my wash bag. So is the toothbrush, toothpaste and comb, but the lipsalve (which I had used everyday) wasn't, nor the flannel or my perfume and several other odds and ends. With that he placed everything back in the 'hot bag' and handed them to me. Chuckling to myself I said my goodbyes. I was free at last!
It struck me that if I had been better informed I could have saved the doctor some time. Old clothes and bathing equipment could have been placed straight in the bin.

I hope this is reassuring to anyone who is about to undergo the same treatment. The only hard part is the loneliness, and that is only for or five days after all.

If it is necessary for you to have the follow-up body scans, you will have a diet to follow. Your body will already be starved of Thyroxin, but you will also have to eliminate iodine from your diet. I found this particularly hard.

You are not allowed to eat any

· Iodised salt
· Milk or dairy produce, including ice cream, cheese, yoghurt etc.
· Eggs
· Seafood including fish, shellfish, kelp or seaweed
· Food containing red food dye, such as red or pink cereals
· Restaurant foods

You have to check ingredient lists and labels to avoid foods containing any of the following:

Iodised salt
Sea salt
Agar agar

Having eaten all these foods for most of my life it was difficult trying to think what I could use as replacements. I love my cup of tea with cows milk, and black tea or coffee I find distasteful. Soya milk might be the answer I thought so I bought some and tried it. Not very pleasant tasting in tea or on cereals, but I could just about stomach it. Then I read the label, it contained sea salt. Some cereals and products like margarine contain whey powder. Many items contain food dyes or gelling agents derived from seaweed. You really do have to look quite carefully at the labels. We don't know what we are eating these days.
Fore-warned is fore-armed though, and you can work out what you can or cannot eat to suit your own palate.

Hoping this reaches somebody who is in the same position as I was, for I am sure it will be of help to them. I only wish I had been better informed. I am fighting fit now and it was all well worth it. Good Luck.

Sheila Cornhill