Thyroid Cancer

Your thyroid is located in the front of your neck, just under your Adam's apple. (Read about "Thyroid") The thyroid produces several hormones, including one called thyroxine, which help regulate a number of bodily functions. The American Cancer Society (ACS) says that about one third of all adults will find they have a lump in their thyroid. Ninety-five percent of those lumps are not cancerous, but they can cause the thyroid to malfunction and need to be checked by a doctor. The other five percent will be diagnosed as cancer. (Read about "Cancer: What It Is") ACS says over 19,000 people will get that news each year, the majority of them women. There is a 3 to 1 ratio of women to men who get thyroid cancer. The National Cancer Institute (NCI) calls thyroid cancer the most common cancer of the endocrine system (Read about "Endocrine System"), resulting in about 1 percent of all cancers. The good news is the treatment success rate for thyroid cancer is very high.

Types of cancer

There are four main types of thyroid cancer. They include:

• Papillary - Called the most common type of thyroid cancer by ACS, it represents 60 to 80 percent of thyroid cancers. It develops in the cells that produce the thyroid hormones containing iodine. It is a slow growing cancer that over 80 percent of the time involves just one side of the thyroid. ACS says that 90 percent of the people treated for this cancer live 15 years or more after they find out they have the disease.
• Follicular - Also develops in the cells that make iodine containing hormones. It represents 10 to 30 percent of thyroid cancers. It is more aggressive than papillary and can spread. Once again, it has a high treatment success rate; about 90 percent of people with it live 15 years or more.
• Medullary - The only cancer that forms in the cells of the thyroid that help control the amount of calcium (Read about "Calcium") in our bodies. It is more likely to spread to other parts of the body. It is also the only thyroid cancer with a clear genetic connection, according to NCI. Five to seven percent of thyroid cancers are this type. Some 80 percent of patients with this cancer are still alive ten years after diagnosis.
• Anaplastic - The most aggressive of the thyroid cancers, grows and spreads quickly. It is relatively rare, responsible for just 2 percent of thyroid cancers. Unfortunately, the survival rate is low as well. ACS says only 3 to 17 percent of patients survive five years after diagnosis.

Symptoms and Risks

The most common symptom of thyroid cancer is a lump. Often that is the only symptom. Also remember, 95 percent of lumps in the thyroid are not cancer but should still be checked by a doctor because they can affect the normal function of the thyroid. (Read about thyroid nodules in "Thyroid" ") Other symptoms according to ACS and NCI can include:

• pain in the neck
• a fullness or tightness in the neck
• problems swallowing or breathing (Read about "Respiratory System")
• hoarseness
• a cough that won't go away and isn't because of a cold

Once again, these symptoms can also indicate other medical conditions and should be checked by a doctor.

Radiation has been identified as one of the major risk factors for thyroid cancer. Years ago, many children were exposed to radiation to treat a number of conditions such as acne or for swollen adenoids or tonsils. (Read about "Acne" "Tonsils & Adenoids") Studies show that those people have an increased risk of thyroid cancers. Exposure to radiation from nuclear fallout in the 1950's is also being studied as a risk factor. The thyroid collects iodine and much of the fallout was in the form of radioactive iodine. There is also evidence according to ACS that there are more thyroid cancers showing up in children who lived near the Chernobyl nuclear plant that exploded in 1986.

Diagnosis and Treatment

Physical examination and scans can be used to discover lumps in the thyroid. Ultimately however, a biopsy (Read about "Biopsy") will be needed to confirm the existence of cancer. Treatment can then be planned. (Read about "Cancer Treatments")

Once cancer of the thyroid is found (diagnosed), more tests will be done to find out if cancer cells have spread to other parts of the body. This is called staging. A doctor needs to know the stage of the disease to plan treatment. The following stages are used for cancers of the thyroid, according to NCI:

Papillary cancers of the thyroid:

• Stage I

  Cancer is only in the thyroid and may be found in one or both lobes.

• Stage II

  In patients younger than 45 years of age:

  • Cancer has spread beyond the thyroid.

  In patients older than 45 years of age:

  • Cancer is only in the thyroid and larger than 1 centimeter (about 1/2 inch).

• Stage III

  Cancer is found in patients older than 45 years of age and has spread outside the thyroid (but not outside of the neck) or has spread to the lymph nodes. (Read about "The Lymph System")

• Stage IV

  Cancer is found in patients older than 45 years of age and has spread to other parts of the body, such as the lungs and bones.

Follicular cancers of the thyroid:

• Stage I

  Cancer is only in the thyroid and may be found in one or both lobes.

• Stage II

  In patients younger than 45 years of age:

  • Cancer has spread beyond the thyroid.

  In patients older than 45 years of age:

  • Cancer is only in the thyroid and larger than 1 centimeter (about 1/2 inch).

• Stage III

  Cancer is found in patients older than 45 years of age and has spread outside the thyroid (but not outside of the neck) or to the lymph nodes.

• Stage IV

  Cancer is found in patients older than 45 years of age and has spread to other parts of the body, such as the lungs and bones.

Medullary cancers of the thyroid:

• Stage I

  Cancer is less than 1 centimeter (about 1/2 inch) in size.

• Stage II

  Cancer is between 1 and 4 centimeters (about 1/2 to 1 1/2 inches) in size.

• Stage III

  Cancer has spread to the lymph nodes.

• Stage IV

  Cancer has spread to other parts of the body.

Anaplastic

• There is no staging system for anaplastic cancer of the thyroid. This type of cancer of the thyroid grows faster than the other types.

NCI says surgery is the most common treatment for thyroid cancer. The thyroid is either completely or partially removed. Surgery to remove the entire thyroid is called a total thyroidectomy. Some patients with papillary or follicular thyroid cancer may be treated with lobectomy, in which the lobe with the cancerous nodule is removed. Lymph nodes may also be removed. Some patients who have a lobectomy receive radioactive iodine therapy or additional surgery to remove remaining thyroid tissue.

In addition to surgery, radioactive iodine therapy (also called radioiodine therapy) may be used. This uses radioactive iodine to destroy thyroid cancer cells. External radiation therapy and/or chemotherapy may also be used. (Read about chemotherapy, radiation and other cancer therapies in "Cancer Treatments")

If the cancer has spread, additional surgery or other treatments may be needed. After thyroid surgery, replacement thyroid hormone may be needed by the patient for the rest of their lives.

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For a list of individual types of cancer, see Cancer: What It Is