The parathyroid glands are responsible for controlling the calcium in the body. There are four parathyroid glands, two on each lobe of the thyroid gland. They are located at the base of the neck.

Parathyroid cancer is an extremely rare type of cancer. Men and women are equally affected. It usually occurs in people older than 30.

The cause of parathyroid cancer is unknown. People with multiple endocrine neoplasia type I have an increased risk for this disease. People who had head or neck radiation may also be at increased risk. Such radiation exposure, however, is more often connected with thyroid cancer.

Parathyroid cancer is a slow growing cancer. It is also extremely hard to diagnose.

Symptoms of parathyroid cancer are primarily caused by hypercalcemia (high levels of calcium in the blood), and may affect various parts of the body. They include:

• Bone pain
• Abnormal fractures
• Frequent urination
• Frequent thirst
• Nausea
• Vomiting
• Poor appetite
• Constipation
• Fatigue
• Muscle weakness
• Kidney stones

Your doctor will perform a physical exam and ask about your medical history.

In about half of all cases, palpation (feeling with hands) can reveal a cancerous parathyroid tumor.

Cancerous parathyroid tumors tend to produce very high amounts of parathyroid hormone (PTH). Tests may include:

• Serum PTH (levels that are more than twice the normal may indicate cancer)
• Serum calcium (levels higher than 14 mg/dL are also suspicious)

Prior to surgery, you will undergo a special radioactive scan of the parathyroid glands. The scan is called the sestamibi scan. You may also have a neck ultrasound.

The following treatments may be used to correcting hypercalcemia due to parathyroid cancer:

• Fluids by IV
• Bisphosphonates (drugs that stop the destruction and reabsorption of bones into the body, such as pamidronate or etidronate)
• Calcitonin (a natural hormone produced by the body that helps control calcium levels)
• Gallium nitrate (a drug that lowers levels of calcium in the blood)

Surgery is the recommended treatment for parathyroid cancer. Very often, it is impossible to know whether a parathyroid tumor is cancerous or not. Your doctor may recommend surgery even without a confirmed diagnosis.

If tests before the surgery can find the suspicious gland, surgery may be unilateral  (done on one side of the neck). If it is not possible to find the problem gland before surgery, the surgeon will look at both sides of your neck.

Chemotherapy and radiation do not work very well in preventing the cancer from coming back (recurrence), although radiation can sometimes help reduce the spread of cancer to the bones. Repeated surgeries for cancer that has returned may increase a person's survival rate and reduce the severe effects of hypercalcemia.

Minimally invasive surgery, using smaller cuts, is becoming more common for parathyroid disease.

The cancer may spread (metastasize) to other places in the body, most commonly the lungs and bones.

The most serious complication of parathyroid cancer is hypercalcemia. Most deaths from parathyroid cancer occur as a result of severe, difficult-to-control hypercalcemia, and not the cancer itself.

The cancer commonly comes back (recur). Additional surgeries may be needed. Complications from surgery can include:

• Hoarseness or voice changes as a result of damage to the nerve that controls the vocal cords
• Scarring
• Infection at the site of surgery
• Hypocalcemia (low levels of calcium in the blood, a potentially life-threatening condition)

Phillip K. Pellitteri PK, Sofferman RA, Randolph GW. Surgical Management of Parathyroid Disorders. In: Cummings CW, Flint PW, Haughey BH, et al. (eds).Otolaryngology Head & Neck Surgery, 4th ed. Philadelphia, Pa: Mosby; 2005

Weigel RJ, Macdonald JS, Haller D, McDougall IR. Cancer of the Endocrine System. In: Abeloff MD, Armitage JO, Niederhuber JE, et al. (eds). Clinical Oncology, 3rd ed. Philadelphia, Pa: Chrchill Livingston; 2004.

National Cancer Institute. Parathyroid Cancer: Treatment. In: Physician Data Query. Available online at http://www.cancer.gov/cancertopics/pdq/treatment/parathyroid. Last accessed on 23 April, 2006.