You have four, pea-sized parathyroid glands located in your neck, near or attached to the back of your thyroid. These glands release parathyroid hormone.
Parathyroid hormone (PTH) helps regulate the amount of calcium in the body. If your calcium becomes too low, PTH helps bring more into your blood. It does this by increasing the reabsorption of calcium from the intestines, reducing the amount of calcium lost in the urine and taking calcium from the bones.
If your parathyroid glands produce too much PTH, you have a condition called hyperparathyroidism. This is often caused by a tumor in one of your parathyroid glands. In most cases, however, the tumor is benign, meaning it is not cancerous. Cancerous parathyroid tumors are rare.
Doctors do not know exactly what causes some people to develop parathyroid cancer. However, there are some risk factors that make you more likely to develop this condition. A well-recognized risk factor is having a family history of parathyroid cancer.
According to the National Cancer Institute, there are two inherited conditions that can increase your likelihood of developing this type of cancer. These are:
- familial isolated hyperparathyroidism
- multiple endocrine neoplasia type 1 syndrome (NCI)
It’s important to remember that this is a very rare condition. If you have a tumor in one of your parathyroid glands, chances are good that it’s benign rather than cancerous. According to the Stanford Medicine Cancer Institute, only about 1 percent of people who are diagnosed with hyperparathyroidism have malignant tumors (Stanford).
Most of the symptoms of parathyroid cancer are not directly caused by the cancer itself. Instead, they result from the hypercalcemia that this type of cancer causes.
Some of these symptoms are obvious consequences of the high calcium levels in your blood and the increasing weakness of your bones. These include:
- pain in your bones
- fractured or broken bones
- kidney stones
Many other symptoms are more generalized. For example, you may feel:
- muscle weakness
- more thirsty than usual
You might also experience the following possible symptoms:
- frequent and excessive urination
- unexplained weight loss
- appetite loss
- stomach ulcers
- vocal changes like hoarseness
- pain in your side, back, or abdomen that doesn’t improve
- difficulty thinking clearly
It can be very difficult for a doctor to diagnose parathyroid cancer. This is usually because it’s hard to tell the rare cancerous parathyroid tumors apart from the much more common benign parathyroid tumors.
If your doctor suspects you might have this condition, he or she will often start the diagnostic process by feeling your neck. According to City of Hope (a California-based cancer treatment center), cancerous parathyroid tumors can be felt over 30 percent of the time (City of Hope).
Your doctor will also perform several blood tests. Because a tumor causes your glands to release too much PTH, he or she will check the amount of PTH in your blood. High levels of PTH cause your blood calcium level to rise, so your doctor will also check your blood calcium levels.
If your doctor does these tests and still suspects parathyroid cancer, he or she will perform imaging tests. Possible tests include:
- CT scan
- angiogram (X-ray with special contrast dye)
- sestamibi/SPECT scan (a scan that uses the protein sestamibi and a radioactive material to locate abnormalities of the parathyroid gland). SPECT stands for “single proton emission computerized tomography.”
Treatment for parathyroid cancer usually involves two aspects: getting rid of the cancer and treating the high levels of calcium in your blood.
You will generally need surgery to get rid of the tumor. This might be the case even if your doctor is not sure whether the tumor is cancerous or benign.
In some cases, your doctor might not be able to tell which of your parathyroid glands has the tumor. If that is the case, your surgeon will need to check all your glands during the procedure to find the cancerous one.
Treating the high blood calcium levels usually involves medications. In some cases, you might need intravenous fluids.
Parathyroid cancer may metastasize to your lungs, bones, or other parts of your body. Even if the cancer does not metastasize, and the surgeon removes the entire tumor, the cancer may eventually come back.