Thyroid Cancer in Children

The thyroid is a butterfly-shaped gland in the neck that produces hormones that are important for growth and metabolism. Pediatric thyroid cancer (also called thyroid carcinoma) occurs when the cells in the thyroid gland become abnormal and grow out of control.

Thyroid cancer is an uncommon cancer in childhood: Fewer than one in 100,000 children develop thyroid cancer each year. Although it can occur at any age, childhood thyroid cancer is most common in the teenage years, and it is the second most common cancer among adolescents ages 15 to 19.

Thyroid cancer is often detected as a lump in the front of the neck found by the child, a parent, or by a physician during a routine examination. Some thyroid cancers are discovered by chance during medical imaging performed for another reason.

Although thyroid cancer can spread — usually to the lymph nodes in the neck, or less often to the lungs — most children with thyroid cancer respond very well to treatment. Thyroid cancer in children does not behave the same as it does in adult patients, and outcomes in children are generally better than in adults.

There are several types of thyroid cancer:

• Differentiated thyroid carcinoma includes two different types, papillary thyroid carcinoma and follicular thyroid carcinoma. Both of these types of thyroid cancer develop from the cells of the thyroid gland that normally produce thyroid hormone. Papillary carcinoma is the more common type, accounting for about 90 percent of thyroid cancers in children. Follicular carcinoma is less common and accounts for about 10 percent of cases.
• Medullary thyroid carcinoma is very rare and develops in thyroid cells that do not produce thyroid hormone (called C-cells). Medullary thyroid cancer most often occurs in adults. However, there are familial conditions in which children may develop medullary thyroid carcinoma early in childhood or even in infancy. These familial syndromes are called multiple endocrine neoplasia type 2 (MEN2) or familial medullary thyroid cancer (FMTC).
• Anaplastic thyroid cancer is an extremely rare and aggressive type of thyroid cancer that occurs almost exclusively in adults.

Most children who are diagnosed with thyroid cancer feel well at the time of diagnosis, and many have no symptoms at all. While symptoms may vary from child to child, the most common include:

• A lump in the neck
• Swollen lymph nodes in the neck
• A sensation of a lump in the throat when swallowing (or more rarely, difficulty with swallowing)
• Unexplained hoarseness

Keep in mind that similar symptoms can be associated with more common medical problems and conditions. Therefore, it is important to consult your child's physician for a diagnosis if your child has one of these symptoms.

The vast majority of thyroid cancers in children have no known cause. However, there are some known risk factors for developing thyroid cancer, including radiation exposure and certain genetic conditions.

What causes some children to develop thyroid nodules and thyroid cancer is an area of active research in our Thyroid Center.

• Exposure of the thyroid to radiation, including radiation used to treat other cancers, increases the risk of developing thyroid nodules and thyroid cancer. Some other childhood cancers that are sometimes treated with radiation that may affect the thyroid include leukemias, lymphomas, brain tumors, and neuroblastomas, as well as cancers that require a bone marrow transplant. The younger a child is when exposed to radiation, the more the risk of thyroid nodules and cancer is increased.
• Thyroid nodules and cancer can occur as part of certain genetic conditions. Some of these conditions may be inherited (familial), and some can occur just in the child without being present in the parents. Some genetic syndromes that increase the risk of thyroid nodules and cancer include:
  • PTEN hamartoma tumor syndrome may include features like a large head; vascular malformations; neurodevelopmental disorders; and tumors of many organs including the skin, breast, uterus, and thyroid. Thyroid nodules and thyroid cancer can occur in patients with PTEN mutations as young as 6 years old. (PTEN syndromes also include several other syndromes like Cowden syndrome, Bannayan-Riley-Ruvalcaba syndrome, and Proteus syndrome).
  • DICER1 syndrome increases the risk of several types of tumors, including tumors of the lungs (often in infancy), ovaries, kidneys, and thyroid.
  • Familial adenomatous polyposis (FAP) causes the growth of numerous polyps (abnormal growths or tumors) in the gastrointestinal tract. It also causes an increased risk of other tumors, including thyroid cancer.
  • Multiple endocrine neoplasia type 2 (MEN2) is a familial condition that causes medullary thyroid cancer, sometimes in childhood or even infancy, as well as tumors of the adrenal glands (pheochromocytomas) and sometimes the parathyroid glands.
  • Familial medullary thyroid carcinoma (FMTC) is a familial form of medullary thyroid cancer that is similar to MEN2 except that it does not cause any other types of tumors.

The first step in treating a child with thyroid cancer is forming an accurate and complete diagnosis. In addition to a medical history and physical exam, a physician may order a number of different tests to diagnose thyroid cancer and determine whether it has spread.

• Blood tests are used determine if the thyroid is working properly.
• Ultrasound is the best imaging technique to visualize a known or suspected thyroid nodule. Ultrasound uses sound waves to assess the location and characteristics of nodules in the thyroid gland. Because ultrasound uses only sound waves, it does not expose the patient to any harmful radiation.
• Fine-needle aspiration (sometimes called a biopsy) uses a very thin needle to take a sample of a thyroid nodule and/or lymph nodes to gather information about whether the thyroid nodule may be a thyroid cancer.
• Surgery is sometimes needed to determine whether a thyroid nodule is a thyroid cancer, if the result of fine-needle aspiration (biopsy) is not definitive.
• Computerized tomography (CT or CAT) scan is sometimes needed to take detailed images of the neck or chest, to help determine what surgery or other treatments are needed.
• Genetic testing is useful in many cases to determine whether a thyroid cancer may be part of an underlying genetic condition.

Your doctor may discuss other diagnostic tests with you depending on your child’s individual situation. After we complete all necessary testing, our experts will meet together to review and discuss what they have learned about your child's condition. Then we will meet with you and your family to discuss the results and outline the best possible treatment options.

Your child’s care will vary depending on the specific type of thyroid cancer they have. Components of thyroid cancer treatment may include the following.

Surgery is the first and most important treatment for thyroid cancer. Thoroughly and safely removing as much of the tumor as possible is important to ensure the best possible long-term outcome. This often includes removing the entire thyroid gland, and if necessary any lymph nodes in the neck that may contain thyroid cancer. This allows your doctors to form a complete diagnosis of the cancer type and obtain information on the stage of the disease, which will help determine if any further treatments are necessary.

Thyroid surgery is generally safe but rarely can have serious complications. For this reason, it is important that the procedure be performed by an experienced thyroid surgeon. Our thyroid surgeons have extensive experience in pediatric thyroid surgery and work closely with the rest of the Thyroid Center team to provide seamless, coordinated care before, during, and after surgery.

Radioactive iodine therapy may be recommended to destroy any remaining cancer cells after surgery. This therapy uses the natural need of thyroid cells for iodine to treat thyroid cancer cells that may remain in the body after surgery. Radioactive iodine is absorbed by and destroys these remaining thyroid cells, even if they are located in areas that cannot be removed by surgery (like the lungs). In patients with high-risk thyroid cancer, radioactive iodine therapy can improve outcomes and reduce the risk of thyroid cancer recurrence. Radioactive iodine can only be used to treat differentiated types of thyroid cancers, not medullary thyroid cancers.

Hormone therapy is used to replace normal hormones and slow the growth of cancer cells. If the entire thyroid was removed, lifelong treatment with thyroid medication is needed. In patients with high-risk thyroid cancer, giving a slight excess of thyroid medication may improve outcomes and reduce the risk of thyroid cancer recurrence.

Molecular therapies may be effective for patients with advanced differentiated thyroid carcinoma that does not respond to surgery and radioactive iodine therapy, and for patients with advanced medullary thyroid carcinoma. Many of these new, experimental therapies are available in our Thyroid Center as part of research trials.

The prognosis for children with thyroid cancer is excellent, with a long-term survival rate of greater than 95 percent. Outcomes are best when thyroid cancer is detected and treated early.

Children treated for thyroid cancer have higher recurrence rates than adults, especially those with tumors that have spread to the lymph nodes or other sites. Postoperative treatment with radioactive iodine or hormone therapy may help reduce the risk of recurrent disease. Even if disease does recur, outcomes for children with recurrent disease are excellent.

You and your child will need to work with your medical team to monitor the effects of treatment after your child's cancer is in remission. This will likely include visiting the Thyroid Center every year to monitor for recurrence and to manage possible disease complications. The Thyroid Center provides comprehensive follow-up evaluations from their cancer care team, which includes endocrinologists, surgeons, radiologists, oncologists, genetic counselors, social workers, and psychologists.

The team of clinicians in the Thyroid Center at Boston Children’s Hospital treats children and adolescents with thyroid cancer. Founded in 2001, the Thyroid Center is the oldest program of its kind in the country, and one of the only centers in the U.S. devoted exclusively to the care of children with thyroid diseases. The specialists in this multidisciplinary program have expertise in thyroid ultrasound, fine needle aspiration, thyroid surgery, nuclear medicine imaging, and radioactive iodine therapy.

Surgical experience is critical to having the best outcomes from thyroid cancer surgery, so it’s important to take the time to choose a surgeon who specializes in thyroid cancer in children. The rate of surgical complications is higher in children with thyroid cancer than in adults, perhaps because few pediatric surgeons are well versed in its treatment. Fortunately, thyroid cancer grows slowly, which gives families the opportunity to find a skilled pediatric thyroid surgeon or to seek a second opinion.

At Boston Children’s Thyroid Center, our pediatric thyroid surgeons specialize in the care of children and adolescents with thyroid disease, making us one of the most experienced centers of its kind in the country. This breadth and depth of knowledge result in exceptional outcomes and a low rate of surgical complications, which means that you can trust that your child is in the best hands.