Date Updated: 01/21/2020
Thyroid cancer occurs in the cells of the thyroid — a butterfly-shaped gland located at the base of your neck, just below your Adam's apple. Your thyroid produces hormones that regulate your heart rate, blood pressure, body temperature and weight.
Thyroid cancer might not cause any symptoms at first. But as it grows, it can cause pain and swelling in your neck.
Several types of thyroid cancer exist. Some grow very slowly and others can be very aggressive. Most cases of thyroid cancer can be cured with treatment.
Thyroid cancer rates seem to be increasing. Some doctors think this is because new technology is allowing them to find small thyroid cancers that may not have been found in the past.
Thyroid cancer typically doesn't cause any signs or symptoms early in the disease. As thyroid cancer grows, it may cause:
- A lump (nodule) that can be felt through the skin on your neck
- Changes to your voice, including increasing hoarseness
- Difficulty swallowing
- Pain in your neck and throat
- Swollen lymph nodes in your neck
When to see a doctor
If you experience any signs or symptoms that worry you, make an appointment with your doctor.
It's not clear what causes thyroid cancer.
Thyroid cancer occurs when cells in your thyroid undergo genetic changes (mutations). The mutations allow the cells to grow and multiply rapidly. The cells also lose the ability to die, as normal cells would. The accumulating abnormal thyroid cells form a tumor. The abnormal cells can invade nearby tissue and can spread (metastasize) to other parts of the body.
Types of thyroid cancer
Thyroid cancer is classified into types based on the kinds of cells found in the tumor. Your type is determined when a sample of tissue from your cancer is examined under a microscope. The type of thyroid cancer is considered in determining your treatment and prognosis.
Types of thyroid cancer include:
- Papillary thyroid cancer. The most common form of thyroid cancer, papillary thyroid cancer arises from follicular cells, which produce and store thyroid hormones. Papillary thyroid cancer can occur at any age, but most often it affects people ages 30 to 50. Doctors sometimes refer to papillary thyroid cancer and follicular thyroid cancer together as differentiated thyroid cancer.
- Follicular thyroid cancer. Follicular thyroid cancer also arises from the follicular cells of the thyroid. It usually affects people older than age 50. Hurthle cell cancer is a rare and potentially more aggressive type of follicular thyroid cancer.
- Anaplastic thyroid cancer. Anaplastic thyroid cancer is a rare type of thyroid cancer that begins in the follicular cells. It grows rapidly and is very difficult to treat. Anaplastic thyroid cancer typically occurs in adults age 60 and older.
- Medullary thyroid cancer. Medullary thyroid cancer begins in thyroid cells called C cells, which produce the hormone calcitonin. Elevated levels of calcitonin in the blood can indicate medullary thyroid cancer at a very early stage. Certain genetic syndromes increase the risk of medullary thyroid cancer, although this genetic link is uncommon.
- Other rare types. Other very rare types of cancer that start in the thyroid include thyroid lymphoma, which begins in the immune system cells of the thyroid, and thyroid sarcoma, which begins in the connective tissue cells of the thyroid.
Factors that may increase the risk of thyroid cancer include:
- Female sex. Thyroid cancer occurs more often in women than in men.
- Exposure to high levels of radiation. Radiation therapy treatments to the head and neck increase the risk of thyroid cancer.
- Certain inherited genetic syndromes. Genetic syndromes that increase the risk of thyroid cancer include familial medullary thyroid cancer, multiple endocrine neoplasia, Cowden's syndrome and familial adenomatous polyposis.
Thyroid cancer that comes back
Despite treatment, thyroid cancer can return, even if you've had your thyroid removed. This could happen if microscopic cancer cells spread beyond the thyroid before it's removed.
Thyroid cancer may recur in:
- Lymph nodes in the neck
- Small pieces of thyroid tissue left behind during surgery
- Other areas of the body, such as the lungs and bones
Thyroid cancer that recurs can be treated. Your doctor may recommend periodic blood tests or thyroid scans to check for signs of a thyroid cancer recurrence.
Doctors aren't sure what causes most cases of thyroid cancer, so there's no way to prevent thyroid cancer in people who have an average risk of the disease.
Prevention for people with a high risk
Adults and children with an inherited gene mutation that increases the risk of medullary thyroid cancer may consider thyroid surgery to prevent cancer (prophylactic thyroidectomy). Discuss your options with a genetic counselor who can explain your risk of thyroid cancer and your treatment options.
Prevention for people near nuclear power plants
A medication that blocks the effects of radiation on the thyroid is sometimes provided to people living near nuclear power plants. The medication (potassium iodide) could be used in the unlikely event of a nuclear reactor accident. If you live within 10 miles of a nuclear power plant and are concerned about safety precautions, contact your state or local emergency management department for more information.
Tests and procedures used to diagnose thyroid cancer include:
- Physical exam. Your doctor will examine your neck to feel for physical changes in your thyroid, such as thyroid nodules. He or she may also ask about your risk factors, such as past exposure to radiation and a family history of thyroid tumors.
- Blood tests. Blood tests help determine if the thyroid gland is functioning normally.
- Ultrasound imaging. Ultrasound uses high-frequency sound waves to create pictures of body structures. To create an image of the thyroid, the ultrasound transducer is placed on your lower neck. The appearance of your thyroid on the ultrasound helps your doctor determine whether a thyroid nodule is likely to be noncancerous (benign) or whether there's a risk that it might be cancerous.
- Removing a sample of thyroid tissue. During a fine-needle aspiration biopsy, your doctor inserts a long, thin needle through your skin and into the thyroid nodule. Ultrasound imaging is typically used to precisely guide the needle into the nodule. Your doctor uses the needle to remove samples of suspicious thyroid tissue. The sample is analyzed in the laboratory to look for cancer cells.
- Other imaging tests. You may have one or more imaging tests to help your doctor determine whether your cancer has spread beyond the thyroid. Imaging tests may include CT, MRI and nuclear imaging tests that use a radioactive form of iodine.
- Genetic testing. Some people with medullary thyroid cancer may have genetic changes that can be associated with other endocrine cancers. Your family history may prompt your doctor to recommend genetic testing to look for genes that increase your risk of cancer.
Your thyroid cancer treatment options depend on the type and stage of your thyroid cancer, your overall health, and your preferences.
Most thyroid cancers can be cured with treatment.
Treatment may not be needed right away
Very small thyroid cancers that have a low risk of spreading in the body might not need treatment right away. Instead, you might consider active surveillance with frequent monitoring of the cancer. Your doctor might recommend blood tests and an ultrasound exam of your neck once or twice per year.
In some people, the cancer might never grow and never require treatment. In others, growth may eventually be detected and treatment can be initiated.
Most people with thyroid cancer undergo surgery to remove the thyroid. Which operation your doctor might recommend depends on the type of thyroid cancer, the size of the cancer, whether the cancer has spread beyond the thyroid and the results of an ultrasound exam of the entire thyroid gland.
Operations used to treat thyroid cancer include:
- Removing all or most of the thyroid (thyroidectomy). An operation to remove the thyroid gland might involve removing all of the thyroid tissue (total thyroidectomy) or most of the thyroid tissue (near-total thyroidectomy). The surgeon often leaves small rims of thyroid tissue around the parathyroid glands to reduce the risk of damage to the parathyroid glands, which help regulate the calcium levels in your blood.
- Removing a portion of the thyroid (thyroid lobectomy). During a thyroid lobectomy, the surgeon removes half of the thyroid. It might be recommended if you have a slow-growing thyroid cancer in one part of the thyroid and no suspicious nodules in other areas of the thyroid.
- Removing lymph nodes in the neck (lymph node dissection). When removing your thyroid, the surgeon may also remove nearby lymph nodes in the neck. These can be tested for signs of cancer.
Thyroid surgery carries a risk of bleeding and infection. Damage to your parathyroid glands also can occur during surgery, which can lead to low calcium levels in your body.
There's also a risk that the nerves connected to your vocal cords might not work normally after surgery, which can cause vocal cord paralysis, hoarseness, voice changes or difficulty breathing. Treatment can improve or reverse nerve problems.
Thyroid hormone therapy
After thyroidectomy, you may take the thyroid hormone medication levothyroxine (Levoxyl, Synthroid, others) for life.
This medication has two benefits: It supplies the missing hormone your thyroid would normally produce, and it suppresses the production of thyroid-stimulating hormone (TSH) from your pituitary gland. High TSH levels could conceivably stimulate any remaining cancer cells to grow.
Radioactive iodine treatment uses large doses of a form of iodine that's radioactive.
Radioactive iodine treatment is often used after thyroidectomy to destroy any remaining healthy thyroid tissue, as well as microscopic areas of thyroid cancer that weren't removed during surgery. Radioactive iodine treatment may also be used to treat thyroid cancer that recurs after treatment or that spreads to other areas of the body.
Radioactive iodine treatment comes as a capsule or liquid that you swallow. The radioactive iodine is taken up primarily by thyroid cells and thyroid cancer cells, so there's a low risk of harming other cells in your body.
Side effects may include:
- Dry mouth
- Mouth pain
- Eye inflammation
- Altered sense of taste or smell
Most of the radioactive iodine leaves your body in your urine in the first few days after treatment. You'll be given instructions for precautions you need to take during that time to protect other people from the radiation. For instance, you may be asked to temporarily avoid close contact with other people, especially children and pregnant women.
External radiation therapy
Radiation therapy can also be given externally using a machine that aims high-energy beams, such as X-rays and protons, at precise points on your body (external beam radiation therapy). During treatment, you lie still on a table while a machine moves around you.
External beam radiation therapy may be recommended if surgery isn't an option and your cancer continues to grow after radioactive iodine treatment. Radiation therapy may also be recommended after surgery if there's an increased risk that your cancer will recur.
Chemotherapy is a drug treatment that uses chemicals to kill cancer cells. Chemotherapy is typically given as an infusion through a vein. The chemicals travel throughout your body, killing quickly growing cells, including cancer cells.
Chemotherapy isn't commonly used in the treatment of thyroid cancer, but it's sometimes recommended for people with anaplastic thyroid cancer. Chemotherapy may be combined with radiation therapy.
Targeted drug therapy
Targeted drug treatments focus on specific abnormalities present within cancer cells. By blocking these abnormalities, targeted drug treatments can cause cancer cells to die.
Targeted drug therapy for thyroid cancer targets the signals that tell cancer cells to grow and divide. It's typically used in advanced thyroid cancer.
Injecting alcohol into cancers
Alcohol ablation involves injecting small thyroid cancers with alcohol using imaging such as ultrasound to ensure precise placement of the injection. This procedure causes thyroid cancers to shrink.
Alcohol ablation might be an option if your cancer is very small and surgery isn't an option. It's also sometimes used to treat cancer that recurs in the lymph nodes after surgery.
Supportive (palliative) care
Palliative care is specialized medical care that focuses on providing relief from pain and other symptoms of a serious illness. Palliative care specialists work with you, your family and your other doctors to provide an extra layer of support that complements your ongoing care.
Palliative care can be used while undergoing other aggressive treatments, such as surgery, chemotherapy or radiation therapy. Increasingly, it's being offered early in the course of cancer treatment.
When palliative care is used along with all of the other appropriate treatments, people with cancer may feel better and live longer.
Palliative care is provided by a team of doctors, nurses and other specially trained professionals. Palliative care teams aim to improve quality of life for people with cancer and their families.
Coping and support
A diagnosis of thyroid cancer can be frightening. You might feel as if you aren't sure what to do next.
Everyone eventually finds his or her own way of coping with a cancer diagnosis. Until you find what works for you, consider trying to:
- Find out enough about thyroid cancer to make decisions about your care. Write down the details of your thyroid cancer, such as the type, stage and treatment options. Ask your doctor where you can go for more information. Good sources of information to get you started include the National Cancer Institute, the American Cancer Society and the American Thyroid Association.
- Connect with other thyroid cancer survivors. You might find comfort in talking with people in your same situation. Ask your doctor about support groups in your area. Or connect with thyroid cancer survivors online through the American Cancer Society Cancer Survivors Network or the Thyroid Cancer Survivors' Association.
- Control what you can about your health. You can't control whether or not you develop thyroid cancer, but you can take steps to keep your body healthy during and after treatment. For instance, eat a healthy diet full of a variety of fruits and vegetables, get enough sleep each night so that you wake feeling rested, and try to incorporate physical activity into most days of your week.
Preparing for an appointment
If you have signs and symptoms that worry you, start by seeing your family doctor. If your doctor suspects that you may have a thyroid problem, you may be referred to a doctor who specializes in diseases of the endocrine system (endocrinologist).
Because appointments can be brief, and because there's often a lot of information to go over, it's a good idea to be well prepared. Here's some information to help you get ready, and what to expect from your doctor.
What you can do
- Be aware of any pre-appointment restrictions. At the time you make the appointment, be sure to ask if there's anything you need to do in advance, such as restrict your diet.
- Write down any symptoms you're experiencing, including any that may seem unrelated to the reason for which you scheduled the appointment.
- Write down key personal information, including any major stresses or recent life changes.
- Make a list of all medications, vitamins or supplements that you're taking. Don't forget to include any over-the-counter medications.
- Take a family member or friend along. Sometimes it can be difficult to recall all the information provided during an appointment. Someone who accompanies you may remember something that you missed or forgot.
- Write down questions to ask your doctor.
Your time with your doctor is limited, so preparing a list of questions can help you make the most of your time together. List your questions from most important to least important in case time runs out. For thyroid cancer, some basic questions to ask your doctor include:
- What type of thyroid cancer do I have?
- What stage is my thyroid cancer?
- What treatments do you recommend?
- What are the benefits and risks of each treatment option?
- I have other health problems. How can I best manage them together?
- Will I be able to work and do my usual activities during thyroid cancer treatment?
- Should I seek a second opinion?
- Should I see a doctor who specializes in thyroid diseases?
- How quickly do I need to make a decision about thyroid cancer treatment? Can I take some time to consider my options?
- Are there any brochures or other printed material that I can take with me? What websites do you recommend?
- Am I able to access my medical records through an online patient portal?
If any additional questions occur to you during your visit, don't hesitate to ask.
What to expect from your doctor
Your doctor is likely to ask you a number of questions. Being ready to answer them may reserve time to go over points you want to talk about in-depth. Your doctor may ask:
- When did you first begin experiencing symptoms?
- Are your symptoms occasional or continuous?
- How severe are your symptoms?
- Does anything seem to improve your symptoms?
- Does anything seem to make your symptoms worse?
- Have you ever been treated with radiation therapy?
- Have you ever been exposed to fallout from a nuclear accident?
- Does anyone else in your family have a history of goiter or thyroid or other endocrine cancers?
- Have you been diagnosed with any other medical conditions?
- What medications are you currently taking, including vitamins and supplements?