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. But they do know that people who have been exposed to a lot of radiation-either from the environment or from medical treatment-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 radioactive iodine treatment. It rarely needs radiation therapy and 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

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Cause

Experts do not know the exact cause of thyroid cancer. But they do know that 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 treatment, 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 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

Most people do not have any known risk factors for thyroid cancer. If you do have risk factors, they can include:^{1, 2}

• 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.
• Exposure to fallout from nuclear weapons testing, such as the testing that occurred in the United States during the 1950s. But the radiation exposure from the testing in the 1950s was much lower than at Chernobyl and no increased risk of thyroid cancer at this low level of exposure has been proven.²
• A family history of conditions called MEN 2a, MEN 2b, or FMTC (familial medullary thyroid carcinoma). These are caused by an abnormal gene that greatly increases 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.

If you have respiratory symptoms, such as difficulty breathing, difficulty swallowing, or hoarseness, see the topic Respiratory Problems, Age 12 and Older to determine whether you need to see your doctor.

Who To See

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

• Endocrinologists.
• Family medicine physicians.
• General practitioners.
• Internists.
• Nurse practitioners.
• Physician assistants.

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 needle. This test is a simple procedure that can be done in your doctor's office.

You may also have certain blood tests.

• Serum thyroglobulin level. Thyroglobulin levels are usually high in people who have thyroid cancer, but your thyroglobulin level can be high even if you don't have cancer.
• Serum calcitonin. If you have medullary thyroid cancer (MTC), your calcitonin level may be high.
• Carcinoembryonic antigen (CEA). This test helps predict how well treatment may work. If your CEA is high, you may have medullary thyroid cancer, which is harder to treat than other types of thyroid cancer.

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

• 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

The U.S. Preventive Services Task Force does not think there is enough evidence to recommend screening tests for thyroid cancer.³ Screening tests look for a certain health problem before any symptoms appear. 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 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. 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 National Institutes of Health's Web site at: www.cc.nih.gov/ccc/patient_education/pepubs/lowio.pdf.
• 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:

• A blood test to measure your thyroid-stimulating hormone (TSH) level. This test helps your doctor know if you are taking the right amount of thyroid hormone medicine.
• A blood test to measure your thyroglobulin level. This test helps your doctor know if your cancer has come back. Before this test, you may have to stop taking your thyroid hormone medicine for several weeks. This can cause you to have symptoms of hypothyroidism such as fatigue, weakness, weight gain, depression, memory problems, or constipation.
• Serum calcitonin tests, if you had medullary thyroid cancer (MTC).
• A radioiodine scan to see if the cancer has come back or spread to other parts of your body.
• Other imaging tests to look for signs of cancer, such as ultrasounds, X-rays, CT scans and, in rare cases, MRIs or PET scans.

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:

• Surgery to remove any remaining thyroid tissue and involved lymph nodes.
• Radioactive iodine.
• Chemotherapy. Medicines such as doxorubicin and cisplatin may be used for certain types of recurrent thyroid cancer.⁴
• Radiation therapy to the neck. This is rarely used.

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 Thyrogen.

Prevention

Thyroid cancer cannot be prevented. Most people who have thyroid cancer do not have any known risk factors for the disease.

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.

• Home treatment for constipation includes gentle exercise, drinking lots of fluids, and eating lots of fruits, vegetables, and foods that contain fiber. Check with your doctor before using a laxative for your constipation.
• Home treatment for fatigue includes making sure you get extra rest. You may feel most tired at the end of treatment or just after treatment is completed.
• Home treatment for dry skin includes:
  • Leaving the skin alone as much as possible.
  • Using soap and water sparingly.
  • Using a soothing lotion or body cream daily.
  • Not scratching your skin.

  For more information, see the topic Dry Skin and Itching.

• Home treatment for nausea or vomiting will include watching for and treating early signs of dehydration, such as a dry mouth, sticky saliva, and dark yellow urine. Your doctor also may prescribe medicines to control nausea and vomiting.

  For more information on how to deal with these side effects, see:

  Cancer: Controlling nausea and vomiting from chemotherapy.

• Home treatment for diarrhea includes resting your stomach and watching for signs of dehydration. Check with your doctor before using any diarrhea medicines.

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 naps.
• 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 reduces 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 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 two types of thyroid surgery to treat thyroid cancer. Thyroid lobectomy removes a part (or lobe) of your thyroid gland. 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

• 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.
• 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 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 thyroidectomy.

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

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

References

Citations

1. Carling T, Udelsman R (2005). Thyroid tumors section of Cancer of the endocrine system. In VT DeVita Jr et al., eds., Cancer: Principles and Practice of Oncology, 7th ed., pp. 1502-1520. Philadelphia: Lippincott Williams and Wilkins.

2. American Cancer Society (2005). Detailed Guide: Thyroid Cancer. Available online: http://www.cancer.org/docroot/cri/cri_2_3x.asp?dt=43.

3. U.S. Preventive Services Task Force (1996). Screening for thyroid cancer. In Guide to Clinical Preventive Services, 2nd ed., pp. 187-191. Baltimore: Lippincott Williams and Wilkins.

4. National Cancer Institute (2007). Thyroid Cancer (PDQ): Treatment-Health Professional Version. Available online: http://www.cancer.gov/cancertopics/pdq/treatment/thyroid/healthprofessional.

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.liebertpub.com/thy.

• Clark OH, et al. (2002). Thyroid. In M Dollinger et al., eds., Everyone's Guide to Cancer Therapy, 4th ed., pp. 785-794. 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.

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