Thyroid Issues After Childhood Cancer Treatment

What’s the risk?

The thyroid is a gland located in the neck. It makes hormones that are important for controlling metabolism, growth, and development. The thyroid's production of these hormones is controlled by the pituitary gland, which is located in the brain. Thyroid problems can include hypothyroidism (underactive thyroid), hyperthyroidism (overactive thyroid), and thyroid nodules/tumors.

Who is at risk?

People who had radiation that included the brain, thyroid gland, or came close to the thyroid gland (head & neck, upper spine, and upper chest) are at risk for thyroid problems. Survivors treated with radioiodine therapy (I-131) or MIBG therapy are also at risk.

When is the risk a concern?

The risk of thyroid problems continues for your whole life. Hypo- and hyper-thyroidism most often happen between 2 and 5 years after treatment. Thyroid nodules typically develop 10 years or more after treatment. The risk of thyroid issues increases with the amount of radiation received to the area – higher doses of radiation means the risk is higher.

When should I call my provider?

Hypothyroidism

Symptoms of hypothyroidism (the most common complication) are a result of the thyroid not making enough of the hormones. These include:

• Fatigue.
• Weight gain.
• Constipation.
• Dry skin and brittle hair.
• Always feeling cold.
• Mood changes or feeling sad or depressed.

Hyperthyroidism

Symptoms of hyperthyroidism are a result of the thyroid making too much of the hormones. These include:

• Feeling anxious or agitated.
• Problems concentrating.
• Fast heart rate.
• Sweating or feeling hot all the time.
• Diarrhea.
• Weight loss.
• Bulging eyes.

Thyroid Nodules

Thyroid nodules can appear as a painless bump or lump in your neck. Depending on the location, you may be able to feel it or it can press on your throat, causing symptoms such as difficulty swallowing or a change in your voice. Many thyroid nodules will have no noticeable symptoms.

What should I do to monitor for issues?

• Survivors who have had radiation to the brain or neck should have a physical exam by your healthcare provider every year.
• Inform your provider about any symptoms that could be caused by a thyroid issue (as listed above).
• You should have blood tests to check your thyroid function. This includes a TSH (thyroid-stimulating hormone) and T4 level.
• Your provider should examine your thyroid gland. This is done by feeling the thyroid gland. If they felt a lump, you would have a thyroid ultrasound to help determine if the nodule/lump is benign (not cancerous) or concerning (possibly cancerous).
• Children and teens should have their growth evaluated each year as it can be affected by thyroid issues.
• Women who wish to become pregnant should have their thyroid blood levels checked before pregnancy.  Babies born to mothers with thyroid issues have a higher chance of having developmental problems.

How can I learn more about my risk?

• Going to a cancer survivorship clinic can be helpful to learn about your own risk and ways to reduce your risk. Find a clinic on our list or call local cancer centers to see if they have a clinic for childhood cancer survivors.
• Visit the Children’s Oncology Group website to learn more about risks and recommendations.
• Talk with your care team about your plan for follow up care.