Definition

There are several types of thyroid cancer, including:

• Papillary carcinoma (most common type)—It usually grows very slowly and often spreads to lymph nodes in the neck. If caught early, this type of thyroid cancer is often curable.
• Follicular carcinoma (second most common type)—It usually stays in the thyroid gland, but can spread to other parts of the body, such as the lungs and bones. It does not usually spread to the lymph nodes. If caught early, this type of thyroid cancer is often curable.
• Anaplastic carcinoma (rare form of thyroid cancer)—It quickly invades the neck and other parts of the body and is often fatal.
• Medullary thyroid carcinoma (MTC)—This cancer develops from cells in the thyroid gland called C-cells. MTC often spreads to the lymph nodes, lungs, or liver before a thyroid nodule has been discovered. There are two types of MTC:
  • Sporadic MTC
  • Familial medullary thyroid carcinoma (FMTC)
• Thyroid lymphoma (rare type of thyroid cancer)—Many cases occur in people who have a disease called Hashimoto thyroiditis.

Causes

Cancer occurs when cells in the body divide without control or order. Eventually these uncontrolled cells form a growth or tumor. The term cancer refers to malignant growths. These growths can invade nearby tissues including the lymph nodes. Cancer that has invaded the lymph nodes can then spread to other parts of the body.

It is not clear exactly what causes these problems in the cells, but is probably a combination of genetics and environment.

Risk Factors

Thyroid cancer is more common in women, and in people aged 30 years and older. Other factors that may increase your chance of thyroid cancer include:

• Diet low in iodine
• History of radiation to the head, neck, or chest, especially in infancy or childhood
• Family history of thyroid cancer
• Obesity
• Enlargement of the hands, feet, and facial features—acromegaly
• Sjogren’s syndrome
• Exposure to radioactive fallout from nuclear accidents or exposed to nuclear testing area during childhood

Symptoms

Thyroid cancer may cause:

• A lump in the neck, usually over the thyroid
• Neck pain (sometimes going up to the ears)
• Hoarseness
• Difficulty swallowing
• Difficulty breathing
• Persistent cough
• Enlarged lymph glands in the neck

Diagnosis

The doctor will ask about your symptoms and medical history. A physical exam will also be done. This may include a careful examination of your neck to look for lumps or abnormalities.

Tests may include:

• Blood tests
• Thyroid scan
• Ultrasound
• Fine needle aspiration
• Biopsy of thyroid tissue

The physical exam, combined with all of your test results, will help to determine the type and stage of cancer you have. Staging is used to guide your treatment plan. Like other cancers, thyroid cancer is staged from I-IV. Stage I is a very localized cancer, while stage IV indicates a spread to other parts of the body

Treatment

Cancer treatment varies depending on the stage and type of cancer. Options may include:

• Thyroidectomy—Removal of all or part of the thyroid gland.
• Radioactive iodine therapy—Large doses of radioactive iodine are used to destroy the thyroid gland and thyroid cancer without affecting the rest of the body.
• External radiation therapy—To kill cancer cells and shrink tumors. Radiation is directed at the tumor from a source outside the body.

Prevention

Because the exact cause of thyroid cancer is unknown, early detection and treatment lead to better outcomes. Your doctor may recommend screening tests for you. For example:

• Have a thyroid exam every 3 years if you are aged 20-39 years old
• Have a thyroid exam every year if you are aged 40 years or older

Since exposure to radiation is a major risk factor for thyroid cancer, you should:

• Avoid unnecessary exposure to radiation.
• If you have been exposed to radiation of the head, neck, or chest, have frequent checks for thyroid cancer.

Thyroid Cancer Survivors’ Association http://www.thyca.org

Thyroid Foundation of Canada http://www.thyroid.ca

Papillary thyroid cancer. EBSCO DynaMed website. Available at:
http://www.ebscohost.com/dynamed
Updated August 18, 2014. Accessed September 30, 2014.

Thyroid cancer. American Cancer Society website. Available at:
http://www.cancer.org/acs/groups/cid/documents/webcontent/003144-pdf.pdf
Accessed September 30, 2014.

4/7/2014 DynaMed’s Systematic Literature Surveillance
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Wolinski K, Czarnywojtek A, Ruchala M. Risk of thyroid nodular disease and thyroid cancer in patients with acromegay—meta-analysis and systemic review. PLoS One. 2014;9(2):e88787.

7/7/2014 DynaMed’s Systematic Literature Surveillance
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Liang Y, Yang Z, Qin B, Zhong R. Primary Sjogren’s syndrome and malignancy risk: a systematic review and meta-analysis. Ann Rheum Dis. 2014;73(6):1151-1156.

10/1/2014 DynaMed’s Systematic Literature Surveillance.
http://www.ebscohost.com/dynamed:
Bhaskaran K, Douglas I, Forbes H, et al. Body-mass index and risk of 22 specific cancers: a population-based cohort study of 5.24 million UK adults. Lancet. 2014;384(9945):755-765.