Thyroid cancer occurs in cells of the thyroid gland. Normally, thyroid cells grow and divide to make new cells as the body needs them. A mutation (a change in the genes) can allow the cells to grow and multiply too much. Then, new cells form when the body doesn’t need them, and old or damaged cells don’t die as they should. The extra cells can form a mass of tissue called a nodule (also called a growth or tumor). Most nodules aren’t cancerous, but a child with a lump in the lower front of the neck, swollen lymph nodes or other symptoms of concern should be seen by a doctor and may be referred to a pediatric endocrinologist. Early action can get rid of the cancer.
Thyroid cancer isn’t common in children. Often, the cause isn’t known, though unusually high exposure to radiation can cause children to develop thyroid cancer. Far less often, the cause is a mutated gene that’s inherited.
Thyroid cancer may be noticeable as a painless lump. Because pain or other symptoms are very rare, routine exams are an important way to find this cancer early. Our pediatric endocrinologists gather information from their physical examination, blood tests, imaging tests and a biopsy, as needed, to diagnose the problem and develop an individualized care plan.
Treatment varies, depending on the type of cancer and whether it has spread. Surgery to remove the thyroid gland is the first line of treatment. After surgery, our pediatric endocrinologists monitor the child’s health closely and, if needed, use radioactive iodine therapy. The therapy eliminates any remaining thyroid tissue and works on cancer that went to the lymph nodes or other parts of the body. The child takes a daily thyroid hormone tablet throughout life to replace the thyroid hormone the body can no longer make.
Researchers are interested in learning why thyroid cancer has increased in recent decades. One reason is increased use of imaging tests. Also, the newer imaging technologies find small nodules that wouldn’t have been noticed before (usually when the child has a scan for some other reason). The number of larger nodules being found is also steadily rising, but experts don’t know why. Still, thyroid cancer isn’t common in children in the United States. Girls over the age of 15 are most often affected.
The thyroid gland is important because it makes hormones that help control growth, heart rate, blood pressure, body temperature and weight. This bow tie-shaped gland is at the bottom of the neck, attached to the front of the trachea, and near the nerves that control the vocal cords and voice box. The parathyroid glands on the back of the thyroid help keep a healthy level of calcium in the body.
Thyroid cancer in children is usually one of these types:
Papillary thyroid cancer: This is by far the most common type seen in children. It usually grows slowly and responds well to treatment. It can spread via the lymph nodes, usually to the neck or, less often, to the lung.
Follicular thyroid cancer: This is the second most common type seen in children. It usually grows slowly and responds well to treatment. Rarely, it spreads through the blood vessels, especially to the lungs or bones.
Medullary thyroid cancer: This cancer is very uncommon and it usually grows slowly. It begins in C cells in the thyroid gland. It can spread to lymph nodes in the neck or to distant sites, such as the liver, bone or brain. This cancer frequently runs in families (as a component of multiple endocrine neoplasia type 2.) Genetic counseling and testing help identify affected children in these families so they can have the thyroid gland removed to avoid the cancer.
Although some cancers may recur later in life, with early and appropriate treatment few thyroid cancers in children are fatal. A child who has successful surgery and receives appropriate follow-up care can feel well and live a normal life.