Parathyroid cancer is a rare cancer that develops in the tissue of your parathyroid glands. Your parathyroid glands are usually located behind your thyroid — a butterfly-shaped gland in the front of your neck.
Healthcare professionals don’t use the four-stage naming system for parathyroid cancer that’s commonly used for other types of cancers. Instead, parathyroid cancer is categorized in one of three ways:
. Localized: Localized parathyroid cancer means the cancer is found in your parathyroid gland and may have spread to surrounding tissues.
. Metastatic: Metastatic parathyroid cancer means the cancer has spread to other parts of your body, such as your lymph nodes, liver, lungs, bone or pancreas. Approximately 10% to 30% of people who are diagnosed with parathyroid cancer will have metastatic cancer at the time of diagnosis. Most commonly, the cancer will have spread to your lung, bone or liver.
. Recurrent: Recurrent parathyroid cancer means the cancer comes back after initial treatment — typically, surgical removal of the cancerous gland. More than half of people with parathyroid cancer will experience recurrence. Usually, the cancer comes back two to five years after the first surgery, but it could take over 20 years before it returns.
Most people have four pea-sized parathyroid glands located behind their thyroid gland. Like the thyroid, the parathyroid glands are part of your endocrine system. Sometimes, your parathyroid glands can be found along your esophagus or in your chest. These are known as ectopic (in an abnormal place) parathyroid glands.
Your parathyroid glands are in charge of controlling the amount of calcium in your blood by producing parathyroid hormone (PTH). Sometimes, one or more of your parathyroid glands can release (secrete) too much parathyroid hormone. This is known as primary hyperparathyroidism, or pHPT. Too much parathyroid hormone causes the levels of calcium in your blood to rise, a condition known as hypercalcemia.
A parathyroid adenoma is a benign (noncancerous) growth in a parathyroid gland. Parathyroid cancer is when malignant (cancer) cells form in your parathyroid tissue. Within the scope of parathyroid disorders, parathyroid adenomas are much more common than parathyroid cancer.
Both parathyroid cancer and parathyroid adenomas often cause your parathyroid to become overactive and release too much parathyroid hormone (PTH), which causes hypercalcemia. Hypercalcemia can be harmful to your body and health. Because of this, the most common treatment for both parathyroid cancer and parathyroid adenomas is surgical removal of your overactive parathyroid gland.
It can be challenging for healthcare professionals to tell the difference between a benign parathyroid adenoma and parathyroid cancer because their cells look similar. Further testing is needed after the overactive parathyroid gland is surgically removed to determine if it’s an adenoma or cancer.
Hypercalcemia means that there are higher than normal levels of calcium in your blood. People with parathyroid cancer often have hypercalcemia because the cancer causes your parathyroid gland to become overactive and release large amounts of parathyroid hormone (PTH). Parathyroid hormone regulates the amount of calcium in your blood, so too much parathyroid hormone means you’ll have too much calcium in your blood.
Hypercalcemia can be harmful to your health and body. Because of that, it’s just as important to treat hypercalcemia caused by parathyroid cancer as it is to treat the cancer itself.
There are two kinds of parathyroid cancer. The more common of the two types is when the cancer cells cause your parathyroid gland to produce and release too much parathyroid hormone (PTH), which increases calcium levels in your blood.
The other form of parathyroid cancer is non-functioning (also called non-secreting) parathyroid carcinoma (cancer). It differs from the more common form of parathyroid cancer in that, people with non-functioning parathyroid cancer don’t have increased levels of parathyroid hormone and calcium in their blood. Non-functioning parathyroid carcinoma accounts for less than 10% of parathyroid cancer cases, making it extremely rare.
After parathyroid cancer has been diagnosed, further tests are done to determine if the cancer is localized (found in one place), metastatic (the cancer cells have spread to another part of your body) or recurrent (the cancer comes back after treatment) based on testing findings. Healthcare professionals don’t use the four-stage naming system for parathyroid cancer that’s commonly used for other types of cancers.
Parathyroid cancer affects males and females equally. It generally occurs in people over the age of 30.
There isn’t a known cause of parathyroid cancer.
The following rare genetic (inherited by a family member) disorders are considered risk factors for parathyroid cancer:
. Multiple endocrine neoplasia type I (MEN1).
. Familial isolated hyperparathyroidism (FIHP).
. Hyperparathyroidism-jaw tumor syndrome.
Past radiation therapy for your head or neck can also increase your risk of parathyroid cancer.
Most of the symptoms of parathyroid cancer are actually symptoms of hypercalcemia that develop because of it.
Symptoms and signs of hypercalcemia include:
. Having to pee more often than usual (frequent urination).
. Being thirstier than usual.
. Nausea and vomiting.
. Not feeling as hungry as usual.
. Feeling really tired.
. Feeling depressed.
. Forgetfulness or memory loss.
. Muscle aches, weakness and/or cramping.
Other possible symptoms of parathyroid cancer include:
. Having a lump in your neck.
. Experiencing voice changes or hoarseness.
. Difficulty swallowing.
Parathyroid cancer can be challenging to diagnose. One reason for this is that the cells of a benign (noncancerous) parathyroid adenoma and the cells of parathyroid cancer look similar.
A diagnosis of parathyroid cancer is most often made after your abnormal, overactive parathyroid gland has been surgically removed (parathyroidectomy) and further testing is done with the tissue. Sometimes, the surgeon is able to tell during the surgery that it’s parathyroid cancer.
What tests will I have to diagnose parathyroid cancer?
Parathyroid cancer is most often diagnosed after your abnormal, overactive parathyroid gland has been surgically removed (parathyroidectomy) because you were diagnosed with primary hyperparathyroidism. Sometimes, the surgeon is able to diagnose parathyroid cancer during the surgery.
Prior to the surgery to remove your overactive parathyroid gland, you may undergo the following tests and procedures:
. Blood calcium test.
. Blood PTH (parathyroid hormone) test.
. Parathyroid scan (typically a radioactive sestamibi scan and/or CT scan).
If you’ve been diagnosed with parathyroid cancer, you may undergo the following imaging tests so your healthcare provider can determine if the cancer has spread (metastasized) to other parts of your body:
. CT (computerized tomography) scan: A CT scan uses X-rays and a computer to produce many 3D (three-dimensional) images of your body.
. MRI (magnetic resonance imaging): MRI uses a large magnet, radio waves and a computer to produce detailed images of your body. It doesn’t use X-rays (radiation).
Unfortunately, there isn’t a known way to prevent parathyroid cancer. You cannot reduce your risk of getting this condition either. If you have a family history of parathyroid conditions, talk to your healthcare provider.
Surgery to remove the cancerous parathyroid gland (en bloc resection) is the main option for treatment of parathyroid cancer. Your surgeon may also need to remove tissue around your parathyroid gland or cancerous tissues elsewhere in your body if the parathyroid cancer has spread (metastasized).
The following surgical procedures may be used for parathyroid cancer:
. En bloc resection: Your surgeon will remove your entire parathyroid gland and the capsule around it. Your surgeon may need to also remove half of your thyroid gland that’s on the same side as the cancerous parathyroid gland and surrounding tissues, muscle and nerves.
. Tumor debulking: Your surgeon will remove as much of the tumor as possible. Some tumors cannot be completely removed.
. Metastasectomy: Your surgeon will remove any cancer that has spread (metastasized) to other tissues and/or organs in your body, such as your lung.
Chemotherapy and radiation therapy aren’t commonly used to treat parathyroid cancer. Your healthcare provider will determine if there’s a chemotherapy and/or radiation therapy option that’ll work for you.
There aren’t currently any known medications for parathyroid cancer specifically. Most people with parathyroid cancer experience symptoms of hypercalcemia. Since hypercalcemia can be harmful, your healthcare provider may have you take one or more of the following hypercalcemia medications:
. Cinacalcet (Sensipar®).
. Denosumab (XGEVA®).
If you’re experiencing severe symptoms of hypercalcemia, your healthcare provider may recommend immediate hospitalization for IV (intravenous) fluids and other treatments.
Parathyroid cancer can spread (metastasize) to other parts of your body. Approximately 10% to 30% of people who are diagnosed with parathyroid cancer will have metastatic cancer at the time of diagnosis. In metastatic parathyroid cancer cases, the cancer most commonly spreads to your lung, bone or liver, but it could also spread to your lymph nodes or pancreas.
More than half of people diagnosed with parathyroid cancer will experience recurrence (the cancer comes back). Usually, the cancer comes back within a few years — anywhere from two to five years. In some cases, it can even happen decades later (20 years or more) after your original diagnosis and treatment.
The prognosis for parathyroid cancer depends on the completeness of your parathyroid gland removal when you’re is first diagnosed, due to the limited secondary treatment options, like radiation and chemotherapy.
Survival rates for people who have parathyroid cancer and had a complete removal surgery (en bloc resection) with no cancer cells found in the tissue around their cancerous parathyroid gland (negative margins) are up to 90% at five years after the initial surgery and 67% at 10 years after the initial surgery.
More than half of people who’ve been diagnosed with parathyroid cancer and undergo surgery to remove their gland experience recurrence (the parathyroid cancer comes back). In these cases, the cancer usually comes back two to five years after the initial surgery, but it can come even decades later.