Cancer Health Center

Parathyroid cancer is a rare disease in which malignant (cancer) cells form in the tissues of a parathyroid gland.

The parathyroid glands are four pea-sized organs found in the neck near the thyroid gland. The parathyroid glands make parathyroid hormone (PTH or parathormone). PTH helps the body use and store calcium to keep the calcium in the blood at normal levels.

A parathyroid gland may become overactive and make too much PTH, a condition called hyperparathyroidism. Hyperparathyroidism can occur when a benign tumor (noncancer), called an adenoma, forms on one of the parathyroid glands, and causes it to grow and become overactive. Sometimes hyperparathyroidism can be caused by parathyroid cancer, but this is very rare.

The extra PTH causes:

• The calcium stored in the bones to move into the blood.
• The intestines to absorb more calcium from the food we eat.

This condition is called hypercalcemia (too much calcium in the blood).

The hypercalcemia caused by hyperparathyroidism is more serious and life-threatening than parathyroid cancer itself and treating hypercalcemia is as important as treating the cancer.

Having certain inherited disorders can increase the risk of developing parathyroid cancer.

Anything that increases the chance of getting a disease is called a risk factor. Risk factors for parathyroid cancer include the following rare disorders that are inherited (passed down from parent to child):

• Familial isolated hyperparathyroidism (FIHP).
• Multiple endocrine neoplasia type 1 (MEN1) syndrome.

Treatment with radiation therapy may increase the risk of developing a parathyroid adenoma.

Possible signs of parathyroid cancer include weakness, feeling tired, and a lump in the neck.

Most parathyroid cancer symptoms are caused by the hypercalcemia that develops. Symptoms of hypercalcemia include the following:

• Weakness.
• Feeling very tired.
• Nausea and vomiting.
• Loss of appetite.
• Weight loss for no known reason.
• Being much more thirsty than usual.
• Urinating much more than usual.
• Constipation.
• Trouble thinking clearly.

Other symptoms of parathyroid cancer include the following:

• Pain in the abdomen, side, or back that doesn't go away.
• Pain in the bones.
• A broken bone.
• A lump in the neck.
• Change in voice such as hoarseness.
• Trouble swallowing.

Other conditions may cause the same symptoms as parathyroid cancer. A doctor should be consulted if any of these problems occur.

Tests that examine the neck and blood are used to detect (find) and diagnose parathyroid cancer.

Once blood tests are done and hyperparathyroidism is diagnosed, imaging tests may be done to help find which of the parathyroid glands is overactive. Sometimes the parathyroid glands are hard to find and imaging tests are done to find exactly where they are.

Parathyroid cancer may be hard to diagnose because the cells of a benign parathyroid adenoma and a malignant parathyroid cancer look alike. The patient's symptoms, blood levels of calcium and parathyroid hormone, and characteristics of the tumor are also used to make a diagnosis.