What is thyroid cancer?

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.

Almost all thyroid cancers are treated with surgery. After surgery, you may need to take thyroid hormone medicine for the rest of your life. Some people may also need to have radioactive iodine therapy. In cases where surgery isn't possible or radioactive iodine therapy doesn't work, other treatments are available.

In some cases, thyroid cancer can return after treatment. It can show up in the neck area or in another part of the body, such as the lungs. Follow-up care and tests can help catch thyroid cancer early if it returns.

Many people don't have any symptoms when they are diagnosed with thyroid cancer. This cancer is often found when an imaging test, like a CT scan, is done for another reason.

When thyroid cancer grows, it may cause these 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.

There are different types of thyroid cancer. They are based on what the cells look like under a microscope. Your treatment will depend on which type of thyroid cancer you have.

These include:

• Papillary thyroid cancer. This is the most common type of thyroid cancer. It's often only found in one lobe of the thyroid.
• Follicular thyroid cancer. It's found more often in countries where people don't get enough iodine from food.
• Hürthle cell cancer. This is a much less common type. It tends to spread to the lymph nodes in the neck.
• Medullary thyroid cancer. This isn't very common. One type occurs mostly in adults. The other type is inherited and often develops during early childhood.
• Anaplastic thyroid cancer. This is very rare. It's a very aggressive cancer that grows rapidly and is almost always fatal.

Other cancers that can start in the thyroid include lymphoma and sarcoma.

Treatment for thyroid cancer often includes surgery, radioactive iodine, and thyroid hormone therapy. It may include radiation therapy, chemotherapy, or targeted therapy. Very low-risk thyroid cancer may not need treatment right away. With regular checkups and tests, your doctor can closely watch the cancer for any signs of growth (active surveillance).

Your doctor may 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.

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 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 website at www.thyca.org/rai.htm.

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.

To diagnose thyroid cancer, your doctor will ask about your medical history and do a physical exam. You may have tests, including:

• A blood test to check your thyroid-stimulating hormone (TSH) level.
• A thyroid ultrasound.
• A thyroid scan.
• A thyroid uptake scan.

If tests show that cancer is possible, you may have:

• A fine needle biopsy. This removes a small sample of tissue to check for cancer cells.
• Molecular tests. These tests look at cells from your biopsy.
• Surgery. Sometimes the results of a biopsy or other tests aren't enough, and surgery is needed.

Focus on taking care of yourself. Getting enough sleep, eating a healthy diet, and taking medicines as prescribed may help you feel better. Get some physical activity each day if you can, and make time for things you enjoy. Consider joining a support group or talking with a counselor.

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.

Risk factors include:

• Being female.
• Exposure to high levels of radiation, such as after a nuclear power accident.
• A history of radiation treatments to the head, neck, or chest during childhood.
• A personal or family history of thyroid disease or thyroid cancer.
• Inheriting gene changes that can cause thyroid cancer or other inherited conditions, like familial polyposis.

Thyroid cancer is the growth of abnormal cells in your thyroid gland. These cells often form small tumors called nodules. But most thyroid nodules aren't cancer and don't cause harm.

There are several different types of thyroid cancer. The treatment for thyroid cancer is often successful with the right treatment plan.

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.