Thyroid cancer
Thyroid cancer is a disease that starts when cancer cells form in the thyroid gland. Most thyroid cancers are curable, especially when caught early.1
What is the thyroid?
The thyroid is a gland in the front part of the neck, just under what is known as the “Adam’s apple.” The thyroid makes hormones that help regulate heart rate, blood pressure and body temperature. Your thyroid typically can’t be seen or felt.2
The pituitary gland helps control how much thyroid hormone our body releases. It does this using a substance called thyroid-stimulating hormone (TSH). By checking TSH levels, doctors can tell if the thyroid is working as it should. When the thyroid is too active or too weak, it can cause health problems that need to be treated. These include:2
- Hyperthyroidism: This happens when your thyroid makes too much hormone. It can cause symptoms like a fast or irregular heartbeat, trouble sleeping, feeling jittery or nervous, increased hunger, weight loss and feeling too warm.
- Hypothyroidism: This is when your thyroid doesn’t produce enough hormones. It can make you feel constantly tired, slow you down and lead to weight gain.
There are two main types of cells in the thyroid — follicular cells and C cells. Cancer can develop in both of these types of cells.2
- Follicular cells: These cells use iodine from the blood to make thyroid hormones that help maintain your metabolism
- C cells: C cells make a hormone called calcitonin to help control how your body uses calcium
Types of thyroid cancer
There are many types of growths and tumors that can form in the thyroid, but most are not cancerous. When a growth or tumor is cancerous, it can spread to nearby tissues and other parts of the body. The main types of thyroid cancers are:2
Differentiated thyroid cancers are most common. They grow from thyroid follicular cells. Differentiated thyroid cancers can be either papillary, follicular or oncocytic.2
- Papillary thyroid cancer: Papillary thyroid cancer is the most common type of thyroid cancer. About 80% of thyroid cancers are papillary cancers. Typically, papillary thyroid cancers grow slowly and most often develop in only one of the thyroid gland lobes. They can also spread to the lymph nodes in the neck. Even if this happens, the cancer is still rarely fatal and can usually be treated successfully.
- Follicular thyroid cancer: Follicular thyroid cancer is common in regions where people are lacking iodine in their diet. While these cancers typically don’t spread to the lymph nodes, they can spread to other areas of the body like the lungs and bones.
- Oncocytic carcinoma of the thyroid: Oncocytic thyroid cancer is harder to find and treat, making up about 3% of thyroid cancers
Medullary thyroid cancer develops from C cells, the cells in the thyroid gland that help control the amount of calcium in the blood. MTC can be more difficult to detect and treat. It usually spreads to the lymph nodes, lungs or liver before a thyroid nodule is found.2
There are 2 types of MTC:2
- Sporadic MTC: It usually only affects one thyroid lobe and is mostly found in older adults
- Familial MTC: This type is inherited and often develops during childhood or early adulthood. MTC cancer usually shows up in several areas of both thyroid gland lobes.
Anaplastic thyroid cancer often develops from an existing papillary or follicular cancer. It is known to spread quickly into the neck and to other parts of the body and can be difficult to treat.2
Thyroid cancer symptoms
Thyroid cancer doesn’t typically have symptoms early on. They usually begin when the tumor gets bigger. Other conditions may cause the same signs or symptoms. Check with your doctor if you have any of the following: 3,4
- A lump in the front or side of your neck that may grow quickly
- Neck pain (in front)
- Neck swelling
- Trouble breathing
- Trouble or pain swallowing
- Hoarseness
- Constant cough not from a common cold
Other conditions that aren’t cancer can cause thyroid cancer-like symptoms. For example, lumps in the thyroid are common and usually not cancerous. That said — if you have any of these symptoms, tell your doctor.
How is thyroid cancer diagnosed?
If thyroid cancer is suspected, your health care team will use tests to make a diagnosis. Thyroid cancer is also sometimes found during routine physical exams.
Your doctor may use the following tests and procedures:3
- Physical exam: Your doctor checks for lumps or swelling in the neck, voice box and lymph nodes. They also look at your health, habits and medical history.
- Laryngoscopy: A small tool with a light is used to check if the voice box and vocal cords are working normally, especially if a thyroid tumor might be pressing on them
- Blood hormone studies: A blood test checks hormone levels like TSH, calcitonin and antithyroid antibodies to see if anything is unusual
- Blood tests: A blood test looks at things like calcium to find any problems
- Ultrasound exam: Sound waves make a picture of the thyroid. They show how big the nodule is and if it's solid or filled with fluid. It’s also used to guide biopsies.
- Computed tomography (CT) scan: Detailed images of the neck are taken using X-rays
- Fine-needle aspiration biopsy: A thin needle removes small samples of thyroid tissue to check for cancer under a microscope
- Surgical biopsy: A part of the thyroid is removed by surgery to look for cancer
Thyroid cancer treatments
There are different ways to treat thyroid cancer. Some treatments are well-established and commonly used, while others are being explored in clinical trials to see how effective they are. The standard treatments include:3
- Surgery: The most common treatment for thyroid cancer
- Radiation therapy: Uses high-energy X-rays or other types of radiation to kill cancer cells or stop them from growing
- Chemotherapy: Uses drugs to stop the growth of cancer cells by either killing the cells or preventing them from dividing
- Targeted therapy: Drugs that find and attack specific cells that control how cancer grows
Can I prevent thyroid cancer?
Thyroid cancer usually doesn’t have risk factors you can control, which means it’s not something most people can prevent. There are things you can do, however, to lower your risk.2
Limit radiation exposure
Childhood radiation exposure increases thyroid cancer risk. Unless absolutely necessary, doctors avoid head and neck radiation. Imaging tests like X-rays and CT scans use low doses, but doctors minimize their use in children and aim for the lowest radiation dose.2
Preventive thyroid removal
For people with certain conditions or family history, preventive thyroid removal may help. Families with a history of medullary thyroid cancer (MTC) may want to consider genetic testing.2
Who should I see if I’m concerned about thyroid cancer?
If you’re worried about thyroid cancer or experiencing related symptoms, it’s important to talk to your doctor. Start by scheduling an appointment with your primary care physician, who can evaluate your symptoms, perform a physical exam and order initial tests, such as blood work or imaging. If needed, they may refer you to a specialist, such as an endocrinologist, who focuses on hormone-related conditions, or an oncologist if cancer is suspected.
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