Thyroid cancer - papillary carcinoma

Definition

Papillary carcinoma of the thyroid is the most common cancer of the thyroid gland.

See also: Thyroid cancer

Alternative Names

Causes

About 75-85% of all thyroid cancers diagnosed in the United States are papillary carcinoma. It is more common in women than in men. It may occur in childhood, but is typically seen in people between age 20 and 40. 

The cause of this cancer is unknown. A genetic defect may be involved.

High-dose external radiation to the neck increases the risk of developing thyroid cancer. Papillary thyroid cancer in children has also been linked to atomic bomb testing in the Marshall Islands and the 1986 Chernobyl nuclear disaster in the Ukraine.

Radiation given by an I.V. during medical tests and treatments does not increase the risk of developing thyroid cancer.

Symptoms

Thyroid cancer usually begins as a small bump (nodule) in the thyroid gland. However, it should be emphasized that most thyroid bumps are harmless and noncancerous (benign).

Exams and Tests

If you have a lump on your thyroid, your doctor will order blood tests and an ultrasound  of the thyroid gland. 

If the ultrasound shows that the lump is bigger than 1.0 centimeters, a special biopsy called a fine needle aspiration   (FNA) will be performed. This test determines if the lump is cancerous or benign.

Thyroid function tests are usually normal in patients with thyroid cancer.

Treatment

There are three types of  thyroid cancer treatment:

• Surgery
• Radioactive iodine
• Medication

Surgery is done to remove as much of the cancer as possible. The bigger the lump, the more of the thyroid gland must be removed. Frequently, the entire gland is taken out.

After the surgery, most (but not all) patients receive radioactive iodine, which is usually taken by mouth. This substance kills any remaining thyroid tissue. It also helps make medical images more clear, so doctors can see if there is any additional cancer.

If surgery is not an option, external radiation therapy can be useful.

After surgery, the patient will need to take medication called levothyroxine sodium for the rest of their life. This replaces the hormone that they thyroid would normally make.

The patient will need a blood test every 3 to 6 months to check thyroid levels, and an imaging test called a radioactive iodine (I-131) uptake scan  once a year.

Outlook (Prognosis)

The survival rate for papillary thyroid cancer is excellent. More than 95% of adults with such cancer survive at least 10 years. The prognosis is better for patients younger than 40 and for those with smaller tumors.

The following factors may decrease the survival rate:

• Large tumor
• Age over 40
• Cancer has spread to soft tissue
• Cancer has spread to distant parts of the body

Possible Complications

Complications include:

• Accidental removal of the parathyroid gland, which helps regulate blood calcium levels
• Damage to a nerve that controls the vocal cords
• Spreading of cancer to lymph nodes (rare)
• Spreading of cancer to other sites (metastasis)

When to Contact a Medical Professional

Call your health care provider if you have a lump in your neck. 

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Hemminki K. Familial risks for nonmedullary thyroid cancer. J Clin Endocrinol Metab. 2005; 90(10): 5747-53.

Kumar V, Abbas AK, Fausto N. Robbins and Cotran Pathologic Basis of Disease. 7th ed. St. Louis, MO: WB Saunders; 2005:1177-1180.