Parathyroid cancer is a neuroendocrine tumour that develops in the parathyroid glands. The parathyroid glands are four, pea-shaped organs found in the neck near the thyroid gland. These glands produce the parathyroid hormone (PTH or parathormone), which is responsible for the storage and regulation of calcium in the body.
Neuroendocrine cancers are a complex group of tumours that develop in the neuroendocrine system, which is responsible for regulating important bodily functions such as heart rate, blood pressure and metabolism. They most commonly develop in the gastro-intestinal tract, pancreas and the lungs; however, they can develop anywhere in the body. These tumours develop from neuroendocrine cells, which are responsible for receiving signals from the nervous system and producing hormones and peptides (small proteins) in response.
Parathyroid cancers are found equally in men and women, and is most commonly found in people between the ages of 40-60. However, they can develop at any age.
Treatment
If a parathyroid cancer is detected, it will be staged and graded based on size, metastasis (whether the cancer has spread to other parts of the body) and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.
Cancers can be staged using the TNM staging system:
- T (tumour) indicates the size and depth of the tumour.
- N (nodes) indicates whether the cancer has spread to nearby lymph nodes.
- M (metastasis) indicates whether the cancer has spread to other parts of the body.
This system can also be used in combination with a numerical value, from stage 0-IV:
- Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissue.
- Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
- Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localised cancer.
- Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localised cancer.
- Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advanced or metastatic cancer.
Cancers can also be graded based on the rate of growth and how likely they are to spread:
- Grade I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
- Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
- Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.
Once your tumour has been staged and graded, your doctor may recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.
Treatment is dependent on several factors, including location, stage of disease and overall health.
Treatment options for parathyroid cancers may include:
- Surgery, potentially including:
- En bloc resection (complete removal of the parathyroid gland and the capsule surrounding it).
- Lymphadenectomy (removal of affected lymph nodes).
- Tumour debulking (removal of as much of the tumour as possible).
- Chemotherapy.
- Radiation therapy, potentially including:
- External radiation therapy.
- Internal radiation therapy.
- Targeted therapy.
- Clinical trials.
- Palliative care.
For more information on the treatment options, please refer to the Rare Cancers Australia Treatment Options page.
Risk factors
While the cause of parathyroid cancer remains unknown, certain inherited conditions may increase your risk of developing the disease:
Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.
Early symptoms
Many symptoms of parathyroid cancer develop as the result of hypercalcemia (excess calcium production caused by a tumour pressing against the gland). Hormonal symptoms of parathyroid cancer may include:
- General weakness.
- Fatigue.
- Nausea and/or vomiting.
- Unexplained weight loss/loss of appetite.
- Unusually increased thirst.
- Polyuria (frequent or excessive urination).
- Constipation.
- Difficulties concentrating.
Other symptoms of parathyroid cancer may include:
- Persistent abdominal, side and/or back pain.
- Bone pain.
- Easily broken bones.
- Lump in the neck.
- Changes in the voice, such as hoarseness.
- Difficulties swallowing.
Not everyone with the symptoms above will have cancer, but see your general practitioner (GP) if you are concerned.
Diagnosis/diagnosing
If your doctor suspects you have thyroid cancer, they will order a range of diagnostic tests to confirm the diagnosis, and refer you to a specialist for treatment.
Physical examination
Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they may examine your body to check for any abnormalities. More specifically, they will feel around your parathyroid glands for signs of lumps or tenderness.
Imaging
The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), sestamibi scan, single photon emission computed tomography scan (SPECT scan), angiogram and/or positron emission tomography (PET scan), depending on where it is suspected the cancer is. The doctor may also look at other parts of the body to check for signs of metastasis.
Blood tests
A blood test may be taken to assess your overall health and help guide treatment decisions. A routine blood test includes a calcium test, which measures the level of calcium in the blood to determine if they are within a healthy range. Your doctor may also perform venous sampling, where blood is taken from specific veins to determine if the parathyroid gland is under/overactive.
Biopsy
Once the location(s) of the cancer has been identified, the doctor will perform a biopsy to remove a section of tissue using a needle. The tissue sample will then be analysed for cancer cells.
Prognosis (Certain factors affect the prognosis and treatment options)
While it is not possible to predict the exact course of the disease, your doctor may be able to give you a general idea based on rate and depth of tumour growth, susceptibility to treatment, age, overall fitness, and medical history. Generally, early-stage parathyroid cancers have good prognosis and survival rates. However, if the cancer is advanced and has spread, the prognosis may not be as good and there may be a higher risk of cancer recurrence.
References
Some references are to overseas websites. There may be references to drugs and clinical trials that are not available here in Australia.