Coping when your child has cancer

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Thyroid problems

Some people may develop thyroid problems as a late effect of treatments for cancer during childhood. Most thyroid problems occur within 5 years of finishing treatment. But some people develop thyroid problems up to 20 years after treatment. Treatments that can lead to thyroid problems include certain chemotherapy drugs, other medicines and radiation therapy.

How the thyroid works

The thyroid is a gland in the lower part of the neck. It sits in front of the trachea, or windpipe, and below the larynx, or voice box. The thyroid is part of the endocrine system.

The thyroid makes thyroxine and triiodothyronine. These hormones are involved in growth and mental development. They also help regulate metabolism, which is the chemical processes in the body that create and use energy. The thyroid is controlled by the pituitary gland. The pituitary gland makes thyroid-stimulating hormone (TSH). It releases TSH in response to thyroxine and triiodothyronine levels in the blood.

Diagram of the location and structure of the thyroid gland

Types of thyroid problems

People who are treated for cancer as children may have one or more of the following thyroid problems as a late effect of treatment:

  • hypothyroidism, which is an underactive thyroid
  • hyperthyroidism, which is an overactive thyroid
  • growths on the thyroid that may be non-cancerous (benign) or cancerous (malignant)
  • goitre, which is enlargement of the thyroid gland

Causes

Thyroid problems may occur as a late effect of treatments for some childhood cancers, including:

  • acute lymphoblastic leukemia (ALL)
  • brain tumours
  • Hodgkin lymphoma
  • head and neck cancers

Receiving the following treatments may increase the risk of thyroid problems:

  • radiation therapy to the head or neck
  • total body irradiation (TBI) before a stem cell transplant
  • radioiodine therapy (I-131)
  • high doses of metaiodobenzylguanidine (MIBG), which is sometimes used to treat neuroblastoma
  • surgery to remove the thyroid

The risk of developing thyroid problems is greater for girls than for boys. The risk is also higher for children treated with higher doses of radiation or at a young age.

Symptoms

Signs and symptoms of thyroid problems depend on the type of thyroid problem.

Hypothyroidism

Hypothyroidism is when the thyroid doesn’t make enough thyroid hormone. Signs and symptoms of hypothyroidism are:

  • hoarse voice
  • problems concentrating
  • weakness
  • feeling cold all the time
  • puffiness of the face and hands and around the eyes
  • weight gain
  • dry skin
  • brittle hair and fingernails
  • feeling tired
  • feeling sad or depressed
  • mood changes
  • constipation
  • slowing of normal growth
  • being older when you start puberty
  • muscle and joint aches
  • slow heart rate
  • low blood pressure
  • high cholesterol level
  • low exercise tolerance, which is fatigue or shortness of breath during mild exercise

Hyperthyroidism

Hyperthyroidism is when the thyroid makes too much thyroid hormone. Signs and symptoms of hyperthyroidism are:

  • nervousness
  • anxiety
  • moodiness
  • problems concentrating
  • feeling tired
  • weakness
  • shaky hands, or tremors
  • fast or irregular heartbeat
  • increased sweating
  • feeling hot all of the time
  • diarrhea
  • weight loss
  • irregular menstrual periods
  • bulging, or protruding, eyes
  • neck tenderness and swelling
  • low exercise tolerance, which is fatigue or shortness of breath during mild exercise
  • trouble sleeping
  • increased appetite
  • goitre, which is an enlarged thyroid gland
  • fine, soft hair that falls out

Growths on the thyroid

Growths on the thyroid may cause:

  • hyperthyroid symptoms
  • pain in the neck, jaw or ear
  • difficulty swallowing
  • shortness of breath

Goitre

The main sign of goitre is swelling in the front, lower part of the neck. If the goitre is large, other signs and symptoms may include cough, hoarseness and difficulty swallowing or breathing.

Tell your doctor or healthcare team if you or your child develops these symptoms after treatment for a childhood cancer.

Diagnosis

Thyroid problems are usually diagnosed by:

  • physical exam to check growth and development
  • blood tests to check thyroid-stimulating hormone (TSH) and free thyroxine (T4) levels
  • ultrasound to check the size of the thyroid and if there are nodules (lumps) on it.

Find out more about these tests and procedures.

Managing thyroid problems

If thyroid problems develop as a late effect of treatment for a childhood cancer, your healthcare team will develop a treatment plan. Different treatments are used to manage different thyroid problems.

Hypothyroidism can be treated by taking medicine each day. Most people have to take medicine for the rest of their lives. In some cases, it may be stopped if the thyroid begins to work normally.

Hyperthyroidism may be treated in several ways, including medicine, surgery to remove the thyroid or thyroid ablation. Thyroid ablation is a treatment that destroys the hormone-producing cells with a radioactive substance, such as I-131.

Growths on the thyroid will be tested using ultrasound and biopsy to find out if they are cancerous. Surgery may be done to remove the growths.

Goitre may be treated in different ways depending on the cause. Treatment may include iodine supplements, thyroid hormone supplements, radioactive iodine therapy or surgery to remove all or part of the thyroid gland.

Follow-up

All people who are treated for childhood cancer need regular follow-up. The healthcare team will develop a follow-up plan based on the type of cancer, how it was treated and your needs.

Make sure you tell your doctor all the treatments you received. If you received radiation therapy to the head or neck, you should have a physical exam each year. Follow-up tests may include blood tests to check thyroid-stimulating hormone (TSH) and free thyroxine (T4) levels.

endocrine system

The group of glands and cells in the body that make and release hormones (which control many functions such as growth, reproduction, sleep, hunger and metabolism) into the blood.

The endocrine system is made up of the hypothalamus, pituitary gland, pineal gland, thyroid, parathyroid gland, adrenal gland, pancreatic islet cells (also known as islets of Langerhans) and the ovaries or testicles.

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