Thyroid cancer

Facts

Just like other cells in your body, if thyroid cells change or mutate, they can become cancerous, meaning they divide and grow without their normal controls, and they don’t organize normally.

At Seattle Cancer Care Alliance (SCCA), our thyroid experts—all UW Medicine doctors—evaluate and treat thyroid nodules and every type of thyroid cancer. Thyroid Area

Fast facts

  • Your thyroid gland is in the center of your neck, under several thin layers of muscles and in front of your windpipe (trachea). 
  • This gland makes thyroid hormone, which plays a vital role in many aspects of growth and metabolism, the normal chemical processes of breaking down and building up substances in your body.  
  • It’s common for the thyroid to develop cysts or nodules. Cysts are sacs of fluid, and they aren’t cancer. Nodules are solid lumps, usually small. The vast majority of thyroid nodules are not cancer. 
Thyroid

Evaluating thyroid nodules

Usually, the best way for doctors to evaluate thyroid nodules is with ultrasound imaging. 

Based on what your doctor sees, you might need a biopsy to remove a sample of cells from the nodule with a thin needle, or sometimes surgery, and check them under a microscope for signs of cancer.

A nodule may be:

  • Benign: Not cancer
  • Atypical: Not cancer, but the cells are arranged more densely and in a different pattern than usual
  • Malignant: Cancer

If your pathologist determines the cells are cancerous, you may have other tests to give your doctor more information, such as blood tests and, if you didn’t already have one, an ultrasound.

Types of thyroid cancer

The best treatment plan for you depends in part on the type of thyroid cancer you have. There are several types with a wide range of characteristics.

Types

The best treatment plan for you depends in part on the type of thyroid cancer you have. There are several types with a wide range of characteristics.

  • This is the most common type of thyroid cancer. Eighty in 100 people with thyroid cancer have this type.
  • It develops from thyroid follicular cells, which make thyroid hormone using iodine from the food you eat.
  • It tends to grow slowly over time.  
  • If it spreads outside the thyroid, the most common place is to lymph nodes in the neck near the thyroid gland. Rarely, it can spread further to the lungs or the bones.  
  • The main treatment is surgery. If needed after surgery, this type of cancer can often be treated with radioactive iodine therapy.  
  • This type also develops from thyroid follicular cells, but it is less common. About 15 in 100 people with thyroid cancer have this type.
  • It tends to grow slowly over time.
  • It may spread to other organs such as the lymph nodes, lungs, or bones.
  • The main treatment is surgery. If needed after surgery, this type of cancer can often be treated with radioactive iodine therapy.  
  • Only about five in 100 people with thyroid cancer have this type. 
  • It begins in C cells, which make up a small part of the thyroid. Like normal C cells, medullary thyroid cancer produces a hormone called calcitonin. 
  • This type can be more aggressive, meaning faster growing and more likely to spread to other parts of the body, such as the lymph nodes.
  • The main treatment is surgery. Because this type of cancer starts in C cells (not in thyroid follicular cells, where iodine collects), radioactive iodine therapy is not an effective option. Some patients receive chemotherapy as part of a clinical trial looking for more effective treatments.
  • One in four people with medullary thyroid cancer have a form that is genetically inherited (caused by genes passed down in families). These people sometimes develop other endocrine tumors, such as adrenal and parathyroid gland tumors.  
  • This type is rare, affecting only one to two in every 100 people with thyroid cancer. 
  • It is aggressive and can grow very quickly and invade other structures in the neck as well as spread throughout the body.  
  • It is the most difficult type to treat. Typically, treatment involves chemotherapy and radiation therapy and sometimes surgery.
  • This type makes up less than one in 100 thyroid cancers.
  • It is a very uncommon form of lymphoma — almost always a non-Hodgkin lymphoma — that begins in the immune system cells (lymphocytes) of the thyroid. 
  • It is curable and is treated like other non-Hodgkin lymphomas, usually with chemotherapy and radiation therapy. 

Symptoms

Early thyroid cancer may not cause any symptoms. As a tumor grows slowly over time, it may lead to symptoms such as:

  •  A lump you can feel in the front of your neck
  • Difficulty swallowing
  • Hoarseness or other voice changes
  • If it’s large, pressure on your throat or airway when you lie down

If you have any of these symptoms, see your doctor, who can examine you and order an ultrasound or other tests, if needed.

Risk factors

Environmental, genetic, and sex- or age-related factors may increase your risk for developing thyroid cancer. Having a risk factor means that you have a greater chance of developing the disease, not that you will develop it.

These are risk factors for thyroid cancer:

  • Family history of thyroid disease or thyroid cancer. Having a first-degree relative (a parent, sibling, or child) with thyroid carcinoma is generally the most important risk factor. Even with a family history, thyroid cancer is rare. But it’s important to make sure your health care provider knows about your family history.
  • Age. Though thyroid cancer can occur at any age, about two out of three cases are diagnosed in people age 20 to 55.
  • Female sex. Women are three times more likely to develop thyroid cancer than men.
  • Exposure to radiation. This is now a fairly rare risk factor, but it’s still important. From the 1920s to the 1950s, doctors treated common head and neck ailments, such as acne and enlarged tonsils, with high doses of radiation because the risks were unknown. Also, during the 1950s some people were exposed to radiation during atomic-weapons testing. Others have been exposed because of accidents, such as happened in 1986 at the Chernobyl nuclear power plant in what is now Ukraine.
  • Genetic conditions such as multiple endocrine neoplasia (MEN). Certain genetic mutations increase the risk of thyroid cancer. Familial medullary thyroid cancer occurs because of an abnormal gene that is passed from generation to generation. Most people with MEN type II should have their thyroid glands removed to prevent the development of medullary cancer.
  • Race. Asian/Pacific Islander and white Americans are more likely than African-Americans to have thyroid cancer.