Definition

Thyroid cancer is cancer of the thyroid gland. This gland makes thyroid hormone, and it is found in the front of the neck. Thyroid gland tumors often appear as bumps in the neck, called nodules. In most cases, thyroid nodules are not cancerous. However, those that are cancerous have the potential to spread throughout the body.

Thyroid Cancer

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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's thyroiditis.

Causes

The cause is unknown.

Risk Factors

Factors that may increase the risk 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
• Sex: female
• Age: 30 and over
• Exposure to radioactive fallout (eg, exposed to radiation from nuclear accidents or exposed to nuclear testing area during childhood)

Symptoms

Symptoms may include:

• A lump in the neck
• 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.

Your doctor may order tests, such as:

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

Treatment

Once thyroid cancer is found, staging tests are done to find out if the cancer has spread. Treatment depends on the stage of the cancer. Examples of treatment options include:

• Thyroidectomy —This is the removal of all or part of the thyroid gland.
• Radioactive iodine therapy —This uses large doses of radioactive iodine to destroy the thyroid gland and thyroid cancer without affecting the rest of the body.
• External radiation therapy —This is the use of radiation to kill cancer cells and shrink tumors. Radiation is directed at the tumor from a source outside the body.

If you are diagnosed with thyroid cancer, follow your doctor's instructions .

Prevention

Because the exact cause of thyroid cancer is unknown, finding it early and treating it is the best way to prevent dying from the disease. Your doctor may recommend screening tests for you, for example:

• Have a thyroid exam every three 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.