How common is thyroid cancer?

Thyroid cancer is extremely common. Often it is found incidentally or from a palpable nodule in your neck. There are more aggressive types of thyroid cancer that can present with lymph node metastasis.

What is the general prognosis for thyroid cancer?

The treatment and success rates for a cure are excellent for localized thyroid cancer. Localized thyroid cancer means the cancer is still in the thyroid gland or a few nearby lymph nodes.

Why am I receiving radiation treatment?

Thyroid cancer is primarily treated by surgery, but sometimes radioactive iodine is recommended as a complimentary treatment to eliminate any residual thyroid (or thyroid cancer) cells that may have been left behind by surgery. The thyroid absorbs almost all iodine that enters a body. Therefore, a type of radiation treatment called radioactive iodine (also called I-131) is given as a way to find and destroy any remaining thyroid or thyroid cancer cells.

What is the goal of the radiation treatment for thyroid cancer?

The goal of the radiation treatment is to completely eradicate any thyroid cancer, and to eliminate any residual normal thyroid cells which can interfere with blood monitoring tests. Thyroid cancer can recur (come back) and generally when it does it, it reoccurs in the neck (usually in lymph glands). Radioactive iodine can reduce the chances of thyroid cancer coming back. If the thyroid cancer does come back, it is usually still very treatable.

If I already had surgery why do I need the radiation treatment?

The reason for radiation treatment is not only to kill any residual thyroid cancer cells that the surgeon could not see, but also to completely eliminate any residual thyroid tissue. One of the ways to follow patients with thyroid cancer is with a blood test called a thyroglobulin level. After the thyroid gland has been removed and the remaining thyroid tissue radiated and killed, the thyroglobulin level is often very low to undetectable. This allows your doctor to monitor your blood thyroglobulin levels, and detect any subtle rise in thyroglobulin level which can be a very early sign of thyroid cancer recurrence. When your thyroid gland was surgically removed the surgeon can remove the vast majority of gland, but not all of the thyroid tissue (as some of the thyroid tissue is very close to critical structures, such as the vocal cord nerves, parathyroid glands, and windpipe).

How is radioactive iodine given and how does it work?

The radiation treatment will be given to you in the form of a pill. The iodine in the pill is radioactive, and will destroy of the cells that it goes into. Because thyroid tissue will selectively uptake and store the iodine, there are few impacts to other tissues in the body. The dose that we will give you today is dependent on how much thyroid tissue is remaining and if there are any areas of distant thyroid cancer spread as such as in lymph nodes or lungs.

Are there side-effects from taking the radioactive iodine pill?

The radioactive iodine pill is extremely safe and there are no immediate life-threatening side effects. You are not expected to “feel” anything while you are radioactive.

Some minor side effects of the pill include:

  1. Dry mouth/dry eyes: The reason this occurs is that some of the radioactivity is taken up in the salivary glands and tear glands. This can also cause some mild discomfort or swelling in the salivary glands. To minimize the effects of dry mouth, patients are encouraged to suck on sour candy (the type that will cause you to salivate) which helps flush out the radioactive iodine from the salivary glands. Drinking plenty of water to stay well hydrated is also strongly encouraged. Saline drops or artificial tears can be used to treat dry eyes.
  2. There have been few case reports of temporary loss of taste which resolves over time. This can persist for several months but should eventually go away.
  3. Pain in the upper abdomen/stomach area is rare, but can occur. Please call your primary care doctor or endocrinologist should this occur.

Are there any risks to me or others because of my radiation treatment?

The main risk in this treatment is that we are giving you radiation. Anytime you are exposed to radiation there is always a small chance of developing cancer related to radiation exposure in the future. This risk is quite small but is not zero. For women, the standard lifetime risk of developing breast cancer is 8%. Receiving radioactive iodine may increase your lifetime risk by 1-2%.

Do I need to prepare for radioactive iodine treatment?

Yes. You must be on a low iodine diet for 2 weeks prior to radioactive iodine treatment for thyroid cancer. This helps thyroid cells in your body uptake the radioactive iodine, by making them deprived, and therefore hungry for iodine. You may also be asked to stop thyroid hormone supplements or to take special injections to prepare your body for the iodine treatment.

What radiation safety precautions do I need to obey?

There are basic radiation safety precautions which you will need to comply with after your treatment. The radiologist/nuclear specialist will tell you how long you will need to take these precautions. Factors that impact the length of precautions include the dose of iodine, as well as your exposure to small children (under the age of 10). Although the dose of radiation and risks are low, we don't want you exposing others (especially children) to unnecessary radiation. Because the radiation exposure comes directly from you, as well as from your body’s secretions (e.g., sweat, saliva, urine, feces), we ask you to take the following precautions:

  1. Sleep in a separate bed in a separate room. This is to minimize radiation exposure to anyone who may be sleeping next to you. Hotels stays are typically discouraged as rooms are often only separated by a few layers of dry wall.
  2. You are encouraged to have a separate bathroom to minimize radiation exposure to others. In the event you have to share a bathroom, use your own towel that you should keep with you in your bedroom. After you use the toilet, please flush twice as radiation is excreted in urine and feces.
  3. Keep your laundry separate from others in the house. The reason is that often people share laundry bins and clothes which may be pulled out of the laundry and used again. As some of the radiation is excreted in sweat this will cause radiation to get on others’ clothing. After your “precaution period” is over, wash your clothes separately - including your sheets and towels. This will get rid of most of the radiation. Clean the bathroom you used with disinfecting wipes and empty the trash.
  4. You are not allowed to prepare food for others as radiation will be excreted in your sweat glands and will get onto the food. Other people can prepare food for you (following the low iodine diet).
  5. Please use regular plates and silverware. Do not use plastic plates or plastic utensils. High amounts of iodine in your saliva will contaminate your silverware. Plastic/paper items are likely to go into the trash without being washed, and are not appropriate for transfer to a landfill. Simply washing your plates and silverware with soap and water will remove 99% of the radiation, and this is diluted to safe levels in the water supply.
  6. You are not allowed to go to work. If you are a daycare worker or work around small children that applies, extra time off work may be recommended. If you need a note for work, one will be provided.
  7. You are not allowed to use public transportation, including: trains, planes, buses, or long car trips. Public areas (such as shopping centers, malls, sporting events, concerts, etc.) are also not allowed. You are allowed to leave your house or go for walk - assuming that it is a quiet place with no people around.

Any questions? We encourage you to schedule time with the radiologist prior to your procedure to discuss the precautions and side effects prior to scheduling your treatment.

Download a PDF about Radioactive Iodine Treatment for Thyroid Cancer