Thyroid Cancer

Topic Overview

What is thyroid cancer?

Thyroid cancer is a disease that you get when abnormal cells begin to grow in your thyroid gland. The thyroid gland is shaped like a butterfly and is located in the front of your neck. It makes hormones that regulate the way your body uses energy and that help your body work normally.

Thyroid cancer is an uncommon type of cancer. Most people who have it do very well, because the cancer is usually found early and the treatments work well. After it is treated, thyroid cancer may come back, sometimes many years after treatment.

What causes thyroid cancer?

Experts do not know the exact cause of thyroid cancer. Like other cancers, changes in the DNA of your cells seem to play a role. These DNA changes may include changes that are inherited as well as those that happen as you get older. People who have been exposed to a lot of radiation have a greater chance of getting thyroid cancer.

A dental X-ray now and then will not increase your chance of getting thyroid cancer. But past radiation treatment of your head, neck, or chest (especially during childhood) can put you at risk of getting thyroid cancer. Radiation was used from the 1920s to the 1950s to treat problems such as acne or enlarged tonsils, but it is no longer used to treat health problems other than cancer.

What are the symptoms?

Thyroid cancer can cause several symptoms:

  • You may get a lump or swelling in your neck. This is the most common symptom.
  • You may have pain in your neck and sometimes in your ears.
  • You may have trouble swallowing.
  • You may have trouble breathing or have constant wheezing.
  • Your voice may be hoarse.
  • You may have a frequent cough that is not related to a cold.

Some people may not have any symptoms. Their doctors may find a lump or nodule in the neck during a routine physical exam.

How is thyroid cancer diagnosed?

If you have a lump in your neck that could be thyroid cancer, your doctor may do a biopsy of your thyroid gland to check for cancer cells. A biopsy is a simple procedure in which a small piece of the thyroid tissue is removed, usually with a needle, and then checked.

Sometimes the results of a biopsy are not clear. In this case, you may need surgery to remove all or part of your thyroid gland before you find out if you have thyroid cancer.

How is it treated?

Thyroid cancer is treated with surgery and often radioactive iodine. It rarely needs radiation therapy or chemotherapy. What treatment you need depends on your age, the type of thyroid cancer you have, and the stage of your disease. Stage refers to how severe the disease is and how far, if at all, the cancer has spread.

Your doctor may also remove lymph nodes in your neck to see if cancer has spread beyond the thyroid.

Can thyroid cancer be prevented?

You cannot prevent thyroid cancer.

One rare type of thyroid cancer, called medullary thyroid cancer (MTC), runs in families. A genetic test can tell you if you have a greater chance of getting MTC. If this test shows that you have an increased risk, you can have your thyroid gland removed to prevent thyroid cancer later in life.

Frequently Asked Questions

Learning about thyroid cancer:

Being diagnosed:

Getting treatment:

Living with thyroid cancer:

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Cause

Experts do not know the exact cause of thyroid cancer. Like other cancers, changes in the DNA of your cells seem to play a role. These DNA changes may include changes that are inherited as well as those that happen as you get older. People who have been exposed to a lot of radiation—either from the environment or from medical treatment—have a greater chance of developing thyroid cancer. An occasional dental X-ray will not increase your risk of developing thyroid cancer. But past radiation treatment of your head, neck, or chest (especially during childhood) can increase your chances of developing thyroid cancer. Radiation was used from the 1920s to the 1950s to treat problems such as acne or enlarged tonsils, but it is no longer used to treat noncancerous conditions.

One rare type of thyroid cancer, which is called medullary thyroid cancer (MTC), runs in families. You can inherit a specific gene that increases your risk of developing MTC.

Symptoms

Thyroid cancer can cause many symptoms, including:

  • A lump or swelling in your neck. This is the most common symptom.
  • Pain in your neck and sometimes in your ears.
  • Difficulty swallowing.
  • Difficulty breathing or constant wheezing.
  • Hoarseness that is not related to a cold.
  • A cough that continues and is not related to a cold.

Some people may not have any symptoms. Their doctors may find a lump or nodule in the neck during a routine physical exam.

What Happens

Thyroid cancer is a disease that occurs when abnormal cells begin to grow in the thyroid gland. You may notice a lump in your neck and then go to your doctor. Or your doctor may notice a lump during a routine physical exam or on an imaging test that you are having for another health problem.

Thyroid cancer is usually found before the cancer has spread very far. This means that most people who are treated for thyroid cancer do very well. Treatment for thyroid cancer includes surgery, radioactive iodine therapy, thyroid hormone medicines, and in rare cases, radiation therapy or chemotherapy. After it is treated, thyroid cancer may come back, sometimes many years after treatment.

Before starting your treatment, your doctor needs to find out which of the five types of thyroid cancer you have. A biopsy can identify your type of cancer. During a biopsy, a small piece of thyroid tissue is removed, usually with a fine needle. The thyroid tissue cells are then examined under a microscope.

It is also important to determine the stage of your cancer. Staging is a way for your doctor to tell how far, if at all, the cancer has spread. It also helps your doctor decide what kind of treatment you need. Staging generally depends on your age and the results of tests done after you have had surgery to remove part or all of your thyroid gland. Sometimes lymph nodes in your neck may also be removed and examined to see if cancer is present.

If you have your thyroid gland surgically removed, you will probably have symptoms of hypothyroidism—a lack of thyroid hormone—and you will need to take thyroid hormone medicines for the rest of your life. These medicines help regulate your metabolism and other body functions that are normally influenced by the thyroid gland. For more information, see the topic Hypothyroidism.

What Increases Your Risk

Risk factors for thyroid cancer include:

  • A history of radiation treatments to the head, neck, or chest during childhood. Years ago, radiation was used to treat problems such as acne and fungal scalp infections and to shrink the tonsils and adenoids. Radiation exposure in adulthood does not carry the same risk.
  • Exposure to high levels of radiation, such as occurred after the Chernobyl nuclear power accident in 1986. The risk is increased most for those who were younger than age 15 when they were exposed to radiation.
  • A personal or family history of thyroid disease or thyroid cancer.
  • A family history of conditions such as MEN (multiple endocrine neoplasia) 2a, MEN 2b, or FMTC (familial medullary thyroid carcinoma). These are caused by abnormal genes that greatly increase the risk of getting the medullary form of thyroid cancer.
  • Other inherited medical conditions, such as Gardner's syndrome and familial polyposis.
  • Age. Most cases of thyroid cancer are diagnosed in people who are between the ages of 25 and 65, although it can develop at any age.
  • Being female. Thyroid cancer occurs more frequently in women than it does in men.
  • Being Asian.
  • A diet that is too low in iodine. This is not generally a problem in the United States and Canada, because iodine is added to salt and other foods.

When To Call a Doctor

Call your doctor if you have any of the following symptoms:

  • A lump or swelling in your neck. This is the most common symptom of thyroid cancer.
  • Pain in your neck and sometimes in your ears that doesn't go away and is not caused by a cold or allergies
  • Hoarseness that is not related to a cold
  • Difficulty swallowing
  • Difficulty breathing or constant wheezing
  • A cough that continues and is not related to a cold
  • Bone pain

Watchful Waiting

Watchful waiting is a wait-and-see approach. If you get better on your own, you won't need treatment. If you get worse, you and your doctor will decide what to do next. Watchful waiting is not appropriate if you have symptoms that do not go away or that are getting worse. If you are concerned about your symptoms and think you may have thyroid cancer, call your doctor.

Who To See

Health professionals who can evaluate your symptoms and help determine your risk for thyroid cancer include:

Thyroid cancer is usually treated by endocrinologists, nuclear medicine specialists, surgeons, medical oncologists, and radiation oncologists.

To prepare for your appointment, see the topic Making the Most of Your Appointment.

Exams and Tests

In order to diagnose thyroid cancer, your doctor will ask about your medical history and do a physical exam. Thyroid cancer is most often found during a routine physical exam.

If you have a lump or nodule in your thyroid, your doctor may order a CT scan or an ultrasound to get a better look at your thyroid. If your doctor thinks that the lump or nodule could be cancerous, he or she will do a biopsy of the thyroid gland. A biopsy involves removing a piece of your thyroid, often through a fine needle. This test is a simple procedure that can be done in your doctor's office.

You may also have certain blood tests.

Other tests may be done before, during, or after your treatment for thyroid cancer.

  • Serum thyroglobulin level. This blood test is done after treatment to check if the cancer has returned.
  • Radioactive iodine scans help determine whether thyroid cancer has spread beyond the thyroid gland. These scans are done after surgery to remove the gland.
  • Thyroid ultrasound is a safe and simple way to find out whether a thyroid nodule is solid or fluid-filled (cystic). It can also detect multiple thyroid nodules.
  • A chest X-ray may help identify thyroid cancer that has spread to the lungs. This is not common.
  • A CT scan of the liver may be done to check for any spread of cancer to the liver. This is not common.

In rare cases, when thyroid cancer has significantly spread, an MRI or a PET scan may be done.

If you have medullary thyroid cancer (MTC), a CT scan of the chest and belly and a bone scan may also be needed.

Early Detection

At this time there are not any screening tests for thyroid cancer that work well for people at average risk. Talk to your doctor about whether you need to be screened for thyroid cancer.

People who have a family history of medullary thyroid cancer (MTC) may want to have a genetic test to look for a gene change called an RET mutation. Before you have the test, it is a good idea to talk with a genetic counselor. He or she can help you understand what your test results may mean.

Treatment Overview

You may be shocked to find out that you have thyroid cancer. You may also feel angry, scared, depressed, or anxious. There is no normal or right way to react to or cope with having cancer. Try to remember to take care of yourself and to get help when you need it.

The goal of treatment for thyroid cancer is to get rid of the cancer cells in your body. How this is done depends on your age, the type of thyroid cancer you have, the stage of your cancer, and your general health.

Most people have surgery to remove part or all of the thyroid gland. Sometimes a suspicious lump or nodule has to be surgically removed before you will know if you have cancer or not.

After surgery, you may need treatment with radioactive iodine to destroy any remaining thyroid tissue. When you no longer have all or part of your thyroid gland, you will probably need to take thyroid hormone medicines for the rest of your life. These medicines replace necessary hormones that are normally made by the thyroid gland and prevent you from having hypothyroidism—too little thyroid hormone. For more information on hypothyroidism, see the topic Hypothyroidism.

Initial treatment

Your treatment for thyroid cancer may include:

  • Surgery to remove the part of the thyroid gland that contains cancer. Removing one part (lobe) is called a lobectomy. Removing both lobes is called a total thyroidectomy. Removing all but a very small part of the thyroid is called a near-total thyroidectomy. Lymph nodes may also be removed during surgery.
  • Radioactive iodine, which is used after surgery to destroy any remaining thyroid tissue. After you have your thyroid surgically removed, you may have to wait several weeks before having radioactive iodine treatment to destroy any remaining thyroid tissue. During the waiting period, you may have symptoms of hypothyroidism such as fatigue, weakness, weight gain, depression, memory problems, or constipation.
  • Thyroid-stimulating hormone (TSH) suppression therapy. TSH suppression therapy reduces the TSH in your body, which may help prevent the growth of any remaining cancer cells.
  • If thyroid cancer is advanced when it is diagnosed, initial treatment may also include chemotherapy or radiation therapy.

Ongoing treatment

After treatment for thyroid cancer, you may need to take thyroid hormone medicine for the rest of your life to replace the hormones that your body no longer makes. You will also need follow-up visits with your doctor every 6 to 12 months. In addition to scheduling regular visits, be sure to call your doctor if you notice another lump in your neck or if you have trouble breathing or swallowing.

At your follow-up visits, your doctor may order:

Your test results may show that you need additional treatment.

Treatment if the condition gets worse

Thyroid cancer may come back (recur). If thyroid cancer does recur, it may be found during a physical exam, on an ultrasound, or as a result of increasing thyroglobulin levels. Unlike other types of recurrent cancer, recurrent thyroid cancer is often cured, especially if it has spread only to the lymph nodes in the neck. Recurrent thyroid cancer or thyroid cancer that has spread (metastasized) to other parts of the body is treated with:

Before you have a radioactive iodine scan to see if cancer cells have spread (metastasized), you will need to either stop your thyroid hormone replacement for a while or take thyrotropin alfa.

Prevention

Most cases of thyroid cancer cannot be prevented.

One type of thyroid cancer, called medullary thyroid cancer (MTC), is much more likely if you have a gene change called an RET mutation. This can run in families. If there is a history of conditions called MEN 2a, MEN 2b, or FMTC (familial medullary thyroid carcinoma) in your family, a genetic test can determine whether you have an increased risk for medullary thyroid cancer (MTC). If genetic testing shows that you have an increased risk for MTC, you can have your thyroid gland removed to prevent the development of thyroid cancer later in life. If this gene change is present, even very young children can have their thyroid removed to help prevent future MTC.

Home Treatment

There are certain things you can do to feel better or to reduce the side effects of your treatment for thyroid cancer. For some people, eating healthy foods and getting enough sleep and exercise help control their symptoms.

During treatment, you may also experience:

  • Hair loss. If you need high doses of radioactive iodine treatment, you may have some hair loss, but it is usually very mild. You may be the only one who notices it.
  • Sleep problems. If you have trouble sleeping, you may find it helpful to exercise during the day, have a regular bedtime, and avoid caffeine late in the day.
  • Stress. Having any type of cancer can be very stressful. You may feel better if you talk to others, meet with a counselor, or join a support group for people who have thyroid cancer. Learning relaxation techniques (such as yoga or visualization exercises) may also help reduce your stress.
  • Pain. You may or may not experience pain with your cancer. If you do have pain, your doctor may give you prescription medicines, or you may use home treatment for pain. If you use home treatment, such as taking pain medicine you can buy without a prescription, be sure to discuss this treatment with your doctor.

Medications

Although thyroid cancer is generally treated with surgery, medicines may also be needed to treat the cancer and to replace thyroid hormones.

Medication Choices

Medicines to treat thyroid cancer include:

  • Radioactive iodine, which is used after surgery to destroy any remaining thyroid tissue. After you have your thyroid surgically removed, you may have to wait several weeks before having radioactive iodine treatment to destroy any remaining thyroid tissue. During the waiting period, you may have symptoms of hypothyroidism such as fatigue, weakness, weight gain, depression, memory problems, or constipation. Your doctor may also put you on a low-iodine diet before your treatment. If you are on a low-iodine diet, you cannot eat foods that contain a lot of iodine, such as seafood and baked goods. Depleting your body of iodine may make radioactive iodine treatment more effective because your cells become "hungry" for iodine.
  • Thyroid-stimulating hormone (TSH) suppression therapy to reduce the TSH in your body, which may help prevent the growth of any remaining cancer cells. After treatment for thyroid cancer, you may have to take this same type of thyroid hormone medicine for the rest of your life.
  • Chemotherapy , which sometimes is used to treat thyroid cancer that has come back after surgery and anaplastic thyroid cancer that does not respond to radioactive iodine.
  • Thyroid hormone medicines to replace necessary thyroid hormones that are made by your thyroid gland. If your thyroid gland is surgically removed, you will develop hypothyroidism—having too little thyroid hormone—and you will need to take thyroid hormone medicines for the rest of your life. For more information on hypothyroidism, see the topic Hypothyroidism.

What To Think About

Clinical trials continue to evaluate new treatments for thyroid cancer. Talk with your doctor about clinical trials in your area. Information about ongoing clinical trials is also available from the National Cancer Institute. For more information, see the Other Places to Get Help section of this topic.

Surgery

There are three types of thyroid surgery to treat thyroid cancer. Thyroid lobectomy removes a part (or lobe) of your thyroid gland. Near-total thyroidectomy removes all but a very small part of your thyroid. Total thyroidectomy removes your whole thyroid gland. If the cancer has spread to your lymph nodes, those will also be removed. The decision about which type of surgery to have is based on your age, the type of thyroid cancer you have, how much the cancer has spread, and your general health.

Surgery Choices

  • Total thyroidectomy removes the entire thyroid gland. This is the most common type of surgery, because most people have cancer in both parts (lobes) of the thyroid gland. This type of surgery provides the highest rates of cure and also makes radioactive iodine treatment and TSH suppression therapy work better.
  • Near-total thyroidectomy removes all but a very small part of the thyroid gland. This is done in special cases with smaller tumors or if an experienced surgeon is not available.
  • Thyroid lobectomy removes only one part (lobe) of the thyroid gland. This surgery is an option if your cancer is small and is only in one lobe of your thyroid gland. Lobectomy is less complicated than a thyroidectomy and less likely to lead to hypothyroidism. But people who have this type of surgery have a greater chance of their cancer coming back than people who have a thyroidectomy. Sometimes a lobectomy is done when cancer is suspected but not confirmed. If cancer is found in this case, a procedure called a completion thyroidectomy may be necessary.

During surgery, lymph nodes in the neck may also be removed and tested for cancer cells. If thyroid cancer has spread to the lymph nodes, radioactive iodine will be used to destroy the remaining cancer cells.

What To Think About

Most thyroid cancers grow and spread so slowly that you can delay surgery for a short time if necessary. If you choose to postpone surgery, your thyroid cancer should be watched closely by an endocrinologist.

Surgery to remove only the part of the thyroid gland that contains cancer (lobectomy) is less complicated than total thyroidectomy and less likely to lead to hypothyroidism. But thyroid cancer comes back (recurs) after lobectomy more often than it does after total thyroidectomy.

If you and your doctor decide that you need surgery, it is important to have the procedure done by a highly skilled surgeon at a hospital that has a good success rate. There are fewer problems from surgery when a person has a skilled and experienced surgeon.2

Clinical trials continue to evaluate new treatments for thyroid cancer. Talk with your doctor about clinical trials in your area. Information about ongoing clinical trials is also available from the National Cancer Institute. For more information, see the Other Places to Get Help section of this topic.

Other Treatment

If your thyroid cancer comes back (recurs), you may need radiation therapy to the neck. Radiation therapy is used if radioactive iodine has not worked. It may also be used if you are not healthy enough to have surgery, if your cancer could not be entirely removed during surgery, or if your cancer has spread to your bones.

What to think about

Your doctor may also put you on a low-iodine diet before your treatment. If you are on a low-iodine diet, you cannot eat foods that contain a lot of iodine, such as seafood and baked goods. Depleting your body of iodine may make radioactive iodine treatment more effective because your cells become "hungry" for iodine.

  • Foods to avoid in a low-iodine diet include milk and other dairy products, commercial baked products (including most breads), seafood, and red food dye #3. A low-iodine diet is not the same as a low-salt diet. Most salt in the United States and Canada has iodine added, so low-iodine diets avoid iodized salt, but non-iodized salt is okay to eat.
  • For more information, talk to your doctor or a registered dietitian, or visit the Thyroid Cancer Survivor's Association Web site at www.thyca.org/rai.htm.

The decision to use radiation therapy to treat thyroid cancer that has come back depends on the type of thyroid cancer you have, whether the cancer responds to radioactive iodine, what previous treatments were used, and your general health.

Clinical trials continue to evaluate the best treatments for thyroid cancer. Talk with your doctor about clinical trials in your area. Information about ongoing clinical trials is also available from the National Cancer Institute. For more information, see the Other Places to Get Help section of this topic.

Other Places To Get Help

Organizations

American Academy of Otolaryngology—Head and Neck Surgery (AAO-HNS)
1650 Diagonal Road
Alexandria, VA  22314-2857
Phone: (703) 836-4444
Web Address: www.entnet.org
 

The American Academy of Otolaryngology—Head and Neck Surgery (AAO-HNS) is the world's largest organization of physicians dedicated to the care of ear, nose, and throat (ENT) disorders. Its Web site includes information for the general public on ENT disorders.


American Cancer Society (ACS)
Phone: 1-800-ACS-2345 (1-800-227-2345)
TDD: 1-866-228-4327 toll-free
Web Address: www.cancer.org
 

The American Cancer Society (ACS) conducts educational programs and offers many services to people with cancer and to their families. Staff at the toll-free numbers have information about services and activities in local areas and can provide referrals to local ACS divisions.


American Thyroid Association
6066 Leesburg Pike
Suite 550
Falls Church, VA  22041
Phone: 1-800-THYROID (1-800-849-7643)
(703) 998-8890
Fax: (703) 998-8893
E-mail: thyroid@thyroid.org
Web Address: www.thyroid.org
 

The American Thyroid Association promotes scientific and public understanding of thyroid disorders. It publishes a monthly journal and manages a Web site.


Cancer.Net
Phone: 1-888-651-3036
(571) 483-1300
Fax: (571) 366-9530
E-mail: foundation@asco.org
Web Address: www.cancer.net
 

Cancer.Net is the information Web site of the American Society of Clinical Oncology (ASCO) for people living with cancer and for those who care for them. ASCO is the world's leading professional organization representing physicians of all oncology subspecialties. Cancer.Net provides current oncologist-approved information on living with cancer.


National Cancer Institute (NCI)
NCI Publications Office
6116 Executive Boulevard
Suite 3036A
Bethesda, MD  20892-8322
Phone: 1-800-4-CANCER (1-800-422-6237) 9:00 a.m. to 4:30 p.m. EST, Monday through Friday
TDD: 1-800-332-8615
E-mail: cancergovstaff@mail.nih.gov
Web Address: www.cancer.gov (or https://cissecure.nci.nih.gov/livehelp/welcome.asp# for live help online)
 

The National Cancer Institute (NCI) is a U.S. government agency that provides up-to-date information about the prevention, detection, and treatment of cancer. NCI also offers supportive care to people with cancer and to their families. NCI information is also available to doctors, nurses, and other health professionals. NCI provides the latest information about clinical trials. The Cancer Information Service, a service of NCI, has trained staff members available to answer questions and send free publications. Spanish-speaking staff members are also available.


Related Information

References

Citations

  1. National Cancer Institute (2009). Thyroid Cancer (PDQ): Treatment—Health Professional Version. Available online: http://www.cancer.gov/cancertopics/pdq/treatment/thyroid/healthprofessional.
  2. National Comprehensive Cancer Network (2009). Thyroid carcinoma. NCCN Clinical Practice Guidelines in Oncology, version 1. Available online: http://www.nccn.org/professionals/physician_gls/PDF/thyroid.pdf.

Other Works Consulted

  • American Thyroid Association Guidelines Taskforce (2006). Management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid, 16(2): 1–33. Also available online: http://www.thyroid.org/professionals/publications/documents/Guidelinesthy2006.pdf.
  • Clark OH, et al. (2008). Thyroid. In AH Ko et al., eds., Everyone's Guide to Cancer Therapy: How Cancer Is Diagnosed, Treated and Managed Day to Day, 5th ed., pp. 863–873. Kansas City, MO: Andrews McMeel.
  • Cooper DS, et al. (2007). The thyroid gland. In DG Gardner, D Shoback, eds., Greenspan's Basic and Clinical Endocrinology, 8th ed., pp. 209–280. New York: McGraw-Hill.
  • National Institutes of Health (2006). Preparing to Receive Radioactive Iodine: The Low-Iodine Diet. NIH Clinical Center at the National Institutes of Health. Bethesda, MD: National Institutes of Health. Available online: http://www.cc.nih.gov/ccc/patient_education/pepubs/lowio.pdf.
  • Sarkar SD (2004). Management of thyroid cancer. Applied Radiology, 33(11): 34–45.

Credits

Author Bets Davis, MFA
Editor Maria G. Essig, MS, ELS
Associate Editor Terrina Vail
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Specialist Medical Reviewer Matthew I. Kim, MD - Endocrinology & Metabolism
Last Updated August 13, 2009

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