Radioactive iodine treatment for thyroid cancer

The thyroid gland absorbs nearly all of the iodine in your body. When radioactive iodine (RAI), also known as radioiodine or I-131, is taken into the body as a liquid or capsules, it collects in thyroid cells. The radiation can destroy the thyroid gland and any other thyroid cells (including cancer cells) that take up iodine, with little effect on the rest of the body.

This treatment can be used to destroy any thyroid tissue not removed by surgery or to treat some types of thyroid cancer that have spread to lymph nodes and other parts of the body.

RAI treatment improves the survival rate of patients with papillary or follicular thyroid cancer that has spread to the neck or other parts of the body. This treatment is now standard practice in such cases. But the value of RAI treatment is less clear for patients with small cancers of the thyroid gland that do not seem to have spread, which can often be removed completely with surgery. Discuss the risks and benefits of RAI therapy for you with your doctor.

RAI treatment cannot be used to treat anaplastic and medullary thyroid cancers because these types of cancer do not take up iodine.

Risks and side effects

Your body will give off radiation for some time after you have RAI treatment. How much will depend on the dose used. You might need to be in the hospital for a few days after treatment, staying in a special room to keep others from being exposed to radiation. Some people might not need to stay in the hospital. Once you are allowed to go home after treatment, you will be told how to protect others from radiation and how long you need to do this. These instructions may vary slightly by treatment center. Be sure you know what to do before you leave the hospital.

Short-term side effects of RAI treatment may include:

• Neck soreness and swelling
• Nausea and vomiting
• Salivary glands being tender and swollen
• Dry mouth
• Taste changes

Chewing gum or sucking on hard candy may help with salivary gland problems.

RAI treatment also lowers the amount of tears in some people, leading to dry eyes. If you wear contact lenses ask your doctor how long you should keep them out.

Men who get large total doses of radiation may have lower sperm counts or, rarely, become unable to father a child. RAI may also cause some women to have irregular periods for up to a year after treatment. Many doctors suggest that women avoid getting pregnant for 6 months to a year after treatment. No ill effects have been noted in the children born to parents who received RAI in the past.

Both men and women who have had RAI treatment may have a slightly higher risk of getting leukemia in the future. Doctors don’t agree on just how much this risk is increased, but most of the largest studies have found that this is very rare.

Talk to your health care team if you have any questions about the possible risks and benefits of your treatment.