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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 don't know what causes thyroid cancer. But 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.
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 examination.
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 with 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.
Finding out that you have cancer can be overwhelming. It's common to feel scared, sad, or even angry. Talking to others who have had thyroid cancer may help. Ask your doctor about cancer support groups in your area.
Can thyroid cancer be prevented?
Most thyroid cancer cannot be prevented.
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 reduce your risk for thyroid cancer later in life.
Experts don't know what causes 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.
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 examination.
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 examination 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. 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 type 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 find out 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 the results of your radioactive iodine scan.
If you have your thyroid gland surgically removed, you will probably need to take thyroid hormone medicine for the rest of your life to replace the hormones that were made by your thyroid. Taking it will help regulate your metabolism and other body functions.
What Increases Your Risk
A risk factor for thyroid cancer is something that increases your chance of getting this cancer. Having one or more of these risk factors can make it more likely that you will get thyroid cancer. But it doesn't mean that you will definitely get it. And many people who get thyroid cancer don't have any of these risk factors.
The most common risk factors for thyroid cancer include:
- Being female.
- Exposure to high levels of radiation, such as after a nuclear power accident.
- 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).
- Being Asian.
- A history of radiation treatments to the head, neck, or chest during childhood.
- Other inherited medical conditions, such as Gardner's syndrome and familial polyposis.
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 for MTC.
When should you call your 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
Examinations and Tests
In order to diagnose thyroid cancer, your doctor will ask about your medical history and do a physical examination.
Your doctor may check your vocal cords using a thin tube-like instrument that has a light (laryngoscope).
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 may do a fine needle biopsy of the thyroid gland.
You may also have blood tests to check the levels of your thyroid-stimulating hormone (TSH), serum calcitonin, or carcinoembryonic antigen (CEA).
Other tests may be done before, during, or after your treatment for thyroid cancer.
- Serum thyroglobulin level tests check for remaining cancer.
- Radioactive iodine scans help your doctor find out whether thyroid cancer has spread beyond the thyroid 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 and abnormal lymph nodes in the neck.
In some cases, an MRI, a chest X-ray, a CT scan, 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.
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 counsellor. He or she can help you understand what your test results may mean.
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.
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.
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. Your doctor may order other tests, such as a radioiodine scan, X-rays, or a CT scan.
Side effects of treatment
The side effects of surgery for thyroid cancer are usually mild and last a couple of days. Your doctor will talk to you about medicine you can take if you are having pain. You will likely need to take thyroid hormone medicine for the rest of your life to replace the hormones that your body no longer makes.
The most important side effect of radioactive iodine therapy (RAI) is that you will become radioactive for a period of time. Your doctor will give you written instructions to follow to prevent exposing others to radiation. For more information, see Radioactive Iodine.
Thyroid hormone therapy rarely causes side effects when you have the right dose. Too much or too little thyroid hormone can cause side effects.
Taking high doses of thyroid hormone may cause a rapid or irregular heartbeat. High doses taken over time may also cause weakness in your bones (osteoporosis).
Home treatment may help you manage your side effects.
Treatment if the condition gets worse
Thyroid cancer may come back (recur). If thyroid cancer does recur, it may be found during a physical examination, 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 may be treated with surgery, radioactive iodine, radiation, or chemotherapy.
Your doctor may talk to you about being in a clinical trial. For some people with thyroid cancer, taking part in a clinical trial may be the best treatment choice. Clinical trials for thyroid cancer are looking at targeted therapy with tyrosine kinase inhibitors.
Hospice palliative care
Your doctor may talk to you about hospice palliative care. It can improve your quality of life by helping you manage your symptoms. It can also help you with other concerns that you may have when you are living with a serious illness.
Hospice palliative care providers will work with you to help manage your pain, side effects, and stress. They may help you decide what treatment you want or don't want. And they can help your loved ones understand how to support you. For more information, see the topic Hospice Palliative Care.
You can find more information about treating thyroid cancer online at the:
- Canadian Cancer Society website at www.cancer.ca.
- Thyroid Cancer Canada website at www.thyroidcancercanada.org.
Most cases of thyroid cancer cannot be prevented.
You may be much more likely to get medullary thyroid cancer (MTC) if you have a gene carried by some families. A genetic test can show if you carry this gene. If your test is positive for the gene, you may want to talk with your doctor about having your thyroid removed to prevent getting thyroid cancer later in life.
There are certain things you can do to feel better or to reduce the side effects of your treatment for thyroid cancer. Healthy habits such as eating a balanced diet and getting enough sleep and exercise may help control your symptoms. If you have chemotherapy, your doctor may also give you medicines to control and prevent nausea and vomiting.
You can try home treatments:
- For nausea or vomiting, such as ginger or peppermint tea, gum, or candy.
- For feeling very tired. If you lack energy or become weak easily, try to manage your energy and get extra rest. You may feel most tired at the end of treatment or just after treatment is completed.
- For a dry mouth. Take frequent sips of water throughout the day. Sugar-free gum or sugar-free hard candy will help keep your mouth moist without promoting tooth decay. Tart liquids and foods, such as lemonade or dill pickles, may help stimulate the flow of saliva. There are also saliva substitutes that you can buy at a drug store.
- For hair loss. If you need high doses of radioactive iodine treatment, you may have some hair loss, but it is usually very mild. And you may be the only one who notices it.
Handling the stress of having cancer
Having cancer can be very stressful, and it may feel overwhelming to face the challenges in front of you. Finding new ways of coping with the symptoms of stress may improve your overall quality of life. These ideas may help:
- Get the support you need. Spend time with people who care about you, and let them help you.
- Take good care of yourself. Get plenty of rest, and eat nourishing foods.
- Talk about your feelings. Find a support group where you can share your experience.
- Stay positive. Do things each day that will help you stay calm and relaxed.
Having cancer can change your life in many ways. For support in managing these changes, see the topic Getting Support When You Have Cancer.
Although thyroid cancer is generally treated with surgery, medicines may also be needed to treat the cancer and to replace thyroid hormones.
Medicines to treat thyroid cancer include:
- Radioactive iodine, which is used after surgery to destroy any remaining thyroid tissue.
- TSH suppression therapy to reduce the TSH in your body. This slows the growth of any remaining cancer cells.
- Thyroid hormone medicine to replace necessary thyroid hormones that are made by your thyroid gland. If your thyroid gland is surgically removed, you will likely need to take thyroid replacement pills for the rest of your life.
- Chemotherapy, which sometimes is used to treat thyroid cancer that has come back after surgery and to treat anaplastic thyroid cancer that does not respond to radioactive iodine.
- Targeted therapy with tyrosine kinase inhibitors (TKIs), such as sorafenib and sunitinib. Targeted therapy with TKIs is being studied in clinical trials.
After you have your thyroid surgically removed, you may have to wait several weeks before you have 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 treating you with radioactive iodine. If you are on a low-iodine diet, you cannot eat foods that contain a lot of iodine, such as iodized salt, seafood, and baked goods. Depleting your body of iodine may make radioactive iodine treatment more effective, because your cells become "hungry" for iodine.
After surgery, you may need to take thyroid hormone replacement pills for the rest of your life. Taking these pills rarely causes side effects if you are taking the right amount. But too much thyroid hormone can cause you to feel hot and sweaty. It can also cause weight loss, a fast heart rate, chest pain, cramps, or diarrhea. And too little thyroid hormone can cause you to feel cold and tired. It can also cause weight gain, dry skin, or dry hair.footnote 1
Most people with thyroid cancer have surgery to remove the cancer. You may have part or all of your thyroid removed.
The kind of surgery you have may depend on your age, the type of cancer you have, how much the cancer has spread, and your general health.
- 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.
- Near-total thyroidectomy removes all but a very small part of the thyroid gland. This is done in special cases with smaller tumours or if an experienced surgeon is not available.
- Total thyroidectomy removes the entire thyroid gland. This is the most common type of surgery. It provides the highest rates of cure and also makes radioactive iodine treatment and thyroid hormone therapy work better.
During surgery, lymph nodes in the neck may also be removed and tested for cancer cells (lymphadenectomy). If thyroid cancer has spread to the lymph nodes, radioactive iodine will be used to destroy the remaining cancer cells.
Most thyroid cancers grow and spread so slowly that you can delay surgery for a short time if you need to. 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.footnote 2
Radiation treatment uses high-energy X-rays to kill cancer cells and shrink tumours. It is rarely used for thyroid cancer.
- Foods to avoid for 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 Canada and the United States 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 website at www.thyca.org/rai.htm.
People sometimes use complementary therapies along with medical treatment to help relieve symptoms and side effects of cancer treatments. Some of the complementary therapies that may be helpful include:
- Acupuncture to relieve pain.
- Meditation or yoga to relieve stress.
- Massage or biofeedback to reduce pain and ease tension.
- Breathing exercises for relaxation.
These mind-body treatments may help you feel better. They can make it easier to cope with treatment. They also may reduce chronic low back pain, joint pain, headaches, and pain from treatments.
Before you try a complementary therapy, talk to your doctor about the possible value and potential side effects. Let your doctor know if you are already using any such therapies. They are not meant to take the place of standard medical treatment.
- National Cancer Institute (2012). What You Need to Know About Thyroid Cancer. Available online: http://www.cancer.gov/cancertopics/wyntk/thyroid.
- National Comprehensive Cancer Network (2013). Thyroid carcinoma. NCCN Clinical Practice Guidelines in Oncology, version 1.2013. Available online: http://www.nccn.org/professionals/physician_gls/pdf/thyroid.pdf.
Other Works Consulted
- American Cancer Society (2013). Cancer Facts and Figures 2013. Atlanta: American Cancer Society. Available online: http://www.cancer.org/Research/CancerFactsFigures/CancerFactsFigures/cancer-facts-figures-2013.
- American Thyroid Association Guidelines Taskforce (2009). Revised American Thyroid Association management guidelines for patients with thyroid nodules and differentiated thyroid cancer. Thyroid, 19(11): 1167–1214. Also available online: http://thyroidguidelines.net/revised/taskforce.
- 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.
- Davidge-Pitts CJ, Thompson GB (2015). Thyroid tumors. In VT DeVita Jr et al., eds., DeVita, Hellman, and Rosenberg's Cancer Principles and Practices of Oncology, 10th ed., pp. 1175–1188. Philadelphia: Walters Kluwer.
- National Cancer Institute (2013). Thyroid Cancer Treatment (PDQ)—Health Professional Version. Available online: http://www.cancer.gov/cancertopics/pdq/treatment/thyroid/HealthProfessional.
- National Cancer Institute (2013). Thyroid Cancer Treatment (PDQ)—Patient Version. Available online: http://www.cancer.gov/cancertopics/pdq/treatment/thyroid/Patient.
Current as of:
September 8, 2021
Author: Healthwise Staff
E. Gregory Thompson MD - Internal Medicine
Thomas M. Bailey MD - Family Medicine
Adam Husney MD - Family Medicine
Kathleen Romito MD - Family Medicine
Matthew I. Kim MD - Endocrinology
Current as of: September 8, 2021
Author: Healthwise Staff
Medical Review:E. Gregory Thompson MD - Internal Medicine & Thomas M. Bailey MD - Family Medicine & Adam Husney MD - Family Medicine & Kathleen Romito MD - Family Medicine & Matthew I. Kim MD - Endocrinology
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