Thyroid Problems after Childhood Cancer


Some people who were treated for cancer during childhood may develop hormone problems as a result of changes to a complex system of glands known as the endocrine system. These glands include the thyroid, which makes two hormones that are needed for growth and mental development and to help regulate the body's metabolism. Not enough or too much of these hormones can cause various health problems.

Am I at Risk?

Survivors who received radiation that may have affected the thyroid gland are at risk for thyroid problems. Damage to the thyroid gland after childhood cancer is most often the result of radiation to the following areas:

  • head or brain
  • nose, mouth, or throat
  • neck
  • upper chest
  • spine
  • whole body

Surgical removal of the thyroid gland, radioiodine treatments, and high doses of MIBG (sometimes used to treat neuroblastoma) may also cause thyroid problems.

In addition, those who received radiation that may have affected the pituitary gland— which controls the thyroid gland—are also at risk. Damage to the pituitary gland may occur after radiation to the following areas:

  • head or brain
  • eye or eye socket
  • ear or midfacial area behind the cheekbones
  • nose, mouth, or throat

Finally, these factors also are known to increase risk for thyroid problems after childhood cancer:

  • being female,
  • higher radiation doses, and
  • treatment at a younger age.

What Thyroid Problems Might Occur?

Damage to the thyroid gland might not show up for years after treatment. But, regular check-ups may help find thyroid problems early so that treatment can be started. Several types of thyroid problems may develop.

Underactive Thyroid 

When the thyroid gland is not active enough, it is called hypothyroidism. It's the most common thyroid problem in childhood cancer survivors. When the thyroid gland is underactive, thyroid hormone levels are low and your metabolism slows down.

Symptoms of hypothyroidism may include:

  • feeling tired and listless
  • hoarse voice
  • problems concentrating
  • feeling sad or depressed
  • mood changes
  • constipation
  • weakness
  • feeling cold all the time
  • puffiness around the eyes
  • slowing of normal growth
  • late onset of puberty
  • puffiness of the face and hands
  • weight gain
  • dry skin
  • brittle hair
  • muscle and joint aches
  • slowing of the heart rate
  • low blood pressure
  • high cholesterol level
  • poor exercise tolerance

Overactive Thyroid;

When the thyroid is too active it is called hyperthyroidism. When this occurs, thyroid hormone levels are too high and speed up the body's metabolism.

Symptoms of hyperthyroidism include:

  • jitteriness
  • anxiety
  • problems concentrating
  • feeling tired
  • muscle weakness
  • tremors
  • fast or irregular heatbeat
  • increased sweating
  • feeling hot all of the time
  • diarrhea
  • weight loss
  • irregular menstrual periods
  • bulging eyes
  • neck tenderness and swelling
  • poor exercise tolerance

Growths on the Thyroid;

Many years after radiation, growths may occur on the thyroid. Cancerous and non-cancerous growths usually begin as slow-growing, painless lumps in the neck. Most growths don't cause any symptoms.

Should I Be Checked for Thyroid Problems?

If you are at risk for thyroid problems, you should have a check-up every year that looks for thyroid problems. This annual visit should include evaluation of growth in children and teens, examination of the thyroid gland, and a blood test to measure thyroid hormone levels. During periods of rapid growth your doctor may suggest more frequent monitoring of your thyroid levels.

Female survivors who are at risk for thyroid problems should have their thyroid levels checked before trying to get pregnant. This is because mothers with thyroid disease have a higher chance of having babies with developmental problems. It is also important to monitor thyroid levels during pregnancy.

What If I Have Thyroid Problems?

Thyroid gland problems are easy to treat for the most part.

If your thyroid levels are too high or too low, you may be referred to a doctor who specializes in hormones (an endocrinologist). If a lump is found on your thyroid, you may be referred to a surgeon or other specialist.

  • Hypothyroidism is treated with daily thyroid pills, usually for life. In some cases, treatment may be stopped if the thyroid starts to work normally.
  • Hyperthyroidism may be treated with medicine, by drinking radioactive liquid iodine, or with surgery to remove the thyroid gland. Treatment for hyperthyroidism may cause hypothyroidism, which is then treated with a daily thyroid pill.
  • Thyroid growths need additional testing. Surgery may be performed to remove them.
  • Thyroid cancer treatment involves surgery to remove the cancer. After treatment, you might need to use radioactive iodine to destroy any remaining thyroid tissue. After treatment for thyroid cancer, most people need to take daily thyroid pills.

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