About thyroid cancer
What is thyroid cancer?
- The thyroid gland produces thyroid hormones which are important in the normal regulation of the metabolism of the body.
- Thyroid cancer is three times more common in women than in men.
- There are four major types of thyroid cancer: papillary, follicular, medullary, and anaplastic.
- The cause of thyroid cancer is unknown, but certain risk factors have been identified and include a family history of goiter, exposure to high levels of radiation, and certain hereditary syndromes.
- The National Cancer Institute recommends that anyone who received radiation to the head or neck in childhood be examined by a doctor every one to two years to detect potential thyroid cancer.
- The most common signs and symptoms of thyroid cancer include a lump, or thyroid nodule, that can be felt in the neck, trouble swallowing, throat or neck pain, swollen lymph nodes in the neck, cough, and vocal changes.
- The only certain way to tell whether a thyroid lump is cancerous is by examining the thyroid tissue obtained using a needle or surgery for biopsy. A CEA blood test, physical exam, X-rays, CT scans, PET scans, ultrasounds, and MRIs may also be used to help establish a definitive diagnosis and determine staging.
- Surgery is the most common form of treatment for thyroid cancer that has not spread to other areas of the body. Radiation therapy, chemotherapy, and radioactive iodine treatment are also treatment options for thyroid cancer.
- The survival rate and prognosis of thyroid cancer depends upon a few factors, including the individual's age, the size of the tumor, and whether the cancer has metastasized.
- It is not possible to prevent most cases of thyroid cancer.
What is the thyroid?
The thyroid is a gland at the front of your neck beneath your voice box (larynx). A healthy thyroid is a little larger than a quarter. It usually can't be felt through the skin.
The thyroid has two parts (lobes). A thin piece of tissue (the isthmus) connects the two lobes.
The thyroid makes hormones:
- Thyroid hormone: The thyroid follicular cells make thyroid hormone. This hormone affects heart rate, blood pressure, body temperature, and weight. For example, too much thyroid hormone makes your heart race, and too little makes you feel very tired.
- Calcitonin: The C cells in the thyroid make calcitonin. This hormone plays a small role in keeping a healthy level of calcium in the body.
Four or more tiny parathyroid glands are on the back of the thyroid. These glands make parathyroid hormone. This hormone plays a big role in helping the body maintain a healthy level of calcium.
Picture of the front and the back of the thyroid.
What is cancer?
Cancer begins in cells, the building blocks that make up tissues. Tissues make up the thyroid and other organs of the body.
Normal thyroid cells grow and divide to form new cells as the body needs them. When normal cells grow old or get damaged, they die, and new cells take their place.
Sometimes, this process goes wrong. New cells form when the body does not need them, and old or damaged cells do not die as they should. The buildup of extra cells often forms a mass of tissue called a nodule. It may also be called a growth or tumor.
Most thyroid nodules are benign. Benign nodules are not cancer (malignant):
- Benign nodules:
- Are usually not harmful
- Don't invade the tissues around them
- Don't spread to other parts of the body
- Usually don't need to be removed
- Malignant nodules (thyroid cancer):
- May sometimes be a threat to life
- Can invade nearby tissues and organs
- Can spread to other parts of the body
- Often can be removed or destroyed, but sometimes thyroid cancer returns
Thyroid cancer cells can spread by breaking away from the thyroid tumor. They can travel through lymph vessels to nearby lymph nodes. They can also spread through blood vessels to the lungs, liver, or bones. After spreading, cancer cells may attach to other tissues and grow to form new tumors that may damage those tissues.
See the Staging section for information about thyroid cancer that has spread.
What are the different types of thyroid cancer?
There are several types of thyroid cancer:
- Papillary: In the United States, papillary thyroid cancer is the most common type. About 86 of every 100 people with thyroid cancer have this type. It begins in follicular cells and usually grows slowly. If diagnosed early, most people with papillary thyroid cancer can be cured.
- Follicular: The second most common type is follicular thyroid cancer. A little more than 9 of every 100 people with thyroid cancer have this type. It begins in follicular cells and usually grows slowly. If diagnosed early, most people with follicular thyroid cancer can be treated successfully.
- Medullary: Medullary thyroid cancer is not common. About 2 of every 100 people with thyroid cancer have this type. It begins in C cells and can make abnormally high levels of calcitonin. Medullary thyroid cancer tends to grow slowly. It can be easier to control if it's found and treated before it spreads to other parts of the body.
Medullary thyroid cancer sometimes runs in families.
A change in a gene called RET can be passed from parent to child. Nearly everyone with a changed RET gene develops medullary thyroid cancer. The disease occurs alone, as familial medullary thyroid cancer, or with other cancers, as multiple endocrine neoplasia (MEN) syndrome.
A blood test can usually detect a changed RET gene. If it's found in a person with medullary thyroid cancer, the doctor may suggest that family members also be tested. For those who have a changed gene, the doctor may recommend frequent lab tests or surgery to remove the thyroid before cancer develops.
- Anaplastic: The least common type is anaplastic thyroid cancer. About 1 of every 100 people with thyroid cancer has this type. Most people with anaplastic thyroid cancer are older than 60. The cancer begins in follicular cells of the thyroid. The cancer cells tend to grow and spread very quickly. Anaplastic thyroid cancer is very hard to control.
Tests and treatment options depend on the type of thyroid cancer.
What are the symptoms for thyroid cancer?
Thyroid cancer typically doesn't cause any signs or symptoms early in the disease. As thyroid cancer grows, it may cause:
- A lump 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 of these signs or symptoms, make an appointment with your doctor. Thyroid cancer isn't common, so your doctor may investigate other causes of your signs and symptoms first.
What are the causes for thyroid cancer?
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 throughout the body.
Types of thyroid cancer
The type of thyroid cancer you have determines 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.
- 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.
- 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.
- Anaplastic thyroid cancer. Anaplastic thyroid cancer is a rare and rapidly growing cancer that is very difficult to treat. Anaplastic thyroid cancer typically occurs in adults age 60 and older.
- Thyroid lymphoma. Thyroid lymphoma is a rare form of thyroid cancer that begins in the immune system cells in the thyroid and grows very quickly. Thyroid lymphoma typically occurs in older adults.
What are the treatments for thyroid cancer?
Your thyroid cancer treatment options depend on the type and stage of your thyroid cancer, your overall health, and your preferences.
Most people diagnosed with thyroid cancer have an excellent prognosis, as most thyroid cancers can be cured with treatment.
Treatment may not be needed right away
Treatment might not be needed right away for very small papillary thyroid cancers (papillary microcarcinomas) because these cancers have a low risk of growing or spreading. As an alternative to surgery or other treatments, you might consider active surveillance with frequent monitoring of the cancer. Your health care provider might recommend blood tests and an ultrasound exam of your neck once or twice a year.
In some people, the cancer might never grow and never require treatment. In others, growth may eventually be detected and treatment can begin
Most people with thyroid cancer that requires treatment will undergo surgery to remove part or all of the thyroid. Which operation your health care team might recommend depends on your type of thyroid cancer, the size of the cancer and whether the cancer has spread beyond the thyroid to the lymph nodes. Your care team also considers your preferences when creating a treatment plan.
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. Lobectomy might be recommended if you have a slow-growing thyroid cancer in one part of the thyroid, no suspicious nodules in other areas of the thyroid and no signs of cancer in the lymph nodes.
- Removing lymph nodes in the neck (lymph node dissection). Thyroid cancer often spreads to nearby lymph nodes in the neck. An ultrasound examination of the neck before surgery may reveal signs that cancer cells have spread to the lymph nodes. If so, the surgeon may remove some of the lymph nodes in the neck for testing.
To access the thyroid, surgeons usually make a cut (incision) in the lower part of the neck. The size of the incision depends on your situation, such as the type of operation and the size of your thyroid gland. Surgeons usually try to place the incision in a skin fold where it will be difficult to see as it heals and becomes a scar.
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 as expected after surgery, which can cause hoarseness and voice changes. Treatment can improve or reverse nerve problems.
After surgery, you can expect some pain as your body heals. How long it takes to recover will depend on your situation and the type of surgery you had. Most people start to feel recovered in 10 to 14 days. Some restrictions on your activity might continue. For instance, your surgeon might recommend staying away from strenuous activity for a few more weeks.
After surgery to remove all or most of the thyroid, you might have blood tests to see if all of the thyroid cancer has been removed. Tests might measure:
- Thyroglobulin — a protein made by healthy thyroid cells and differentiated thyroid cancer cells
- Calcitonin — a hormone made by medullary thyroid cancer cells
- Carcinoembryonic antigen — a chemical produced by medullary thyroid cancer cells
These blood tests are also used to look for signs of cancer recurrence.
Thyroid hormone therapy
Thyroid hormone therapy is a treatment to replace or supplement the hormones produced in the thyroid. Thyroid hormone therapy medication is usually taken in pill form. It can be used to:
Replace thyroid hormones after surgery. If your thyroid is removed completely, you'll need to take thyroid hormones for the rest of your life to replace the hormones your thyroid made before your operation. This treatment replaces your natural hormones, so there shouldn't be any side effects once your health care team finds the dose that's right for you.
You might also need thyroid hormone replacement after having surgery to remove part of the thyroid, but not everyone does. If your thyroid hormones are too low after surgery (hypothyroidism), your health care team might recommend thyroid hormones.
- Suppress the growth of thyroid cancer cells. Higher doses of thyroid hormone therapy can suppress the production of thyroid-stimulating hormone (TSH) from your brain's pituitary gland. TSH can cause thyroid cancer cells to grow. High doses of thyroid hormone therapy might be recommended for aggressive thyroid cancers.
Radioactive iodine treatment uses a form of iodine that's radioactive to kill thyroid cells and thyroid cancer cells that might remain after surgery. It's most often used to treat differentiated thyroid cancers that have a risk of spreading to other parts of the body.
You might have a test to see if your cancer is likely to be helped by radioactive iodine, since not all types of thyroid cancer respond to this treatment. Differentiated thyroid cancer types, including papillary, follicular and Hurthle cell, are more likely to respond. Anaplastic and medullary thyroid cancers usually aren't treated with radioactive iodine.
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.
Which side effects you experience will depend on the dose of radioactive iodine you receive. Higher doses may cause:
- 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.
Injecting alcohol into cancers
Alcohol ablation, which is also called ethanol ablation, involves using a needle to inject alcohol into small areas of thyroid cancer. Ultrasound imaging is used to precisely guide the needle. The alcohol causes the thyroid cancer cells to shrink.
Alcohol ablation may be an option to treat small areas of thyroid cancer, such as cancer that's found in a lymph node after surgery. Sometimes it's an option if you aren't healthy enough for surgery.
Treatments for advanced thyroid cancers
Aggressive thyroid cancers that grow more quickly may require additional treatment options to control the disease. Options might include:
Targeted drug therapy. Targeted drug treatments focus on specific chemicals present within cancer cells. By blocking these chemicals, targeted drug treatments can cause cancer cells to die. Some of these treatments come in pill form and some are given through a vein.
There are many different targeted therapy drugs for thyroid cancer. Some target the blood vessels that cancer cells make to bring nutrients that help the cells survive. Other drugs target specific gene changes. Your provider may recommend special tests of your cancer cells to see which treatments might help. Side effects will depend on the specific drug you take.
- Radiation therapy. External beam radiation uses a machine that aims high-energy beams, such as X-rays and protons, to precise points on your body to kill cancer cells. Radiation therapy might be recommended if your cancer doesn't respond to other treatments or if it comes back. Radiation therapy can help control pain caused by cancer that spreads to the bones. Radiation therapy side effects depend on where the radiation is aimed. If it's aimed at the neck, side effects might include a sunburn-like reaction on the skin, a cough and painful swallowing.
- Chemotherapy. Chemotherapy is a drug treatment that uses chemicals to kill cancer cells. There are many different chemotherapy drugs that can be used alone or in combination. Some come in pill form, but most are given through a vein. Chemotherapy may help control fast-growing thyroid cancers, such as anaplastic thyroid cancer. In certain situations, chemotherapy might be used for other types of thyroid cancer. Sometimes chemotherapy is combined with radiation therapy. Chemotherapy side effects depend on the specific drugs you receive.
- Destroying cancer cells with heat and cold. Thyroid cancer cells that spread to the lungs, liver and bones can be treated with heat and cold to kill the cancer cells. Radiofrequency ablation uses electrical energy to heat up cancer cells, causing them to die. Cryoablation uses a gas to freeze and kill cancer cells. These treatments can help control small areas of cancer cells.
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 health care team 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, palliative care is 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, have a better quality of life 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.
Follow-up tests for thyroid cancer survivors
After your thyroid cancer treatment ends, your provider may recommend follow-up tests and procedures to look for signs that your cancer has returned. You may have follow-up appointments once or twice a year for several years after treatment ends.
Which tests you need will depend on your situation. Follow-up tests may include:
- Physical exam of your neck
- Blood tests
- Ultrasound exam of your neck
- Other imaging tests, such as CT and MRI
What are the risk factors for thyroid cancer?
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. Examples of exposure to high levels of radiation include radiation treatments to the head and neck and fallout from sources such as nuclear power plant accidents or weapons testing.
- Certain inherited genetic syndromes. Genetic syndromes that increase the risk of thyroid cancer include familial medullary thyroid cancer and multiple endocrine neoplasia.