Parathyroid Cancer, from the CureRays guide library.

Parathyroid cancer is a very rare cancer of the tiny calcium-controlling glands in the neck; surgery is the main cure, and radiation helps lower the chance of return.

What it is.

Parathyroid cancer is a very rare cancer of the parathyroid glands — four tiny glands, each about the size of a grain of rice, that sit behind the thyroid in the front of the neck. These small glands have a big job: they make parathyroid hormone, which controls the level of calcium in the blood and bones. Most parathyroid tumors are benign (non-cancerous) and the cancerous form is uncommon. The hallmark of parathyroid cancer is a very high blood calcium level, because the cancer pumps out too much parathyroid hormone. This can cause tiredness, excessive thirst and urination, kidney stones, bone pain, stomach upset, and confusion. Often the high calcium causes more trouble than the tumor itself, so controlling calcium is a key part of treatment. A neck lump may sometimes be felt. Because the glands are small and close to important nerves and the thyroid, treatment is led by an experienced endocrine surgery and cancer team. The main treatment is complete surgical removal, and radiation can be added to lower the chance of the cancer returning.

How radiation treats it.

Radiation uses focused high-energy x-rays to damage the DNA inside cancer cells so they can no longer grow and divide. The parathyroid glands sit in a crowded part of the neck, close to the voice box, airway, swallowing muscles, and important nerves, so modern image-guided radiation is carefully shaped to concentrate the dose on the tumor area while protecting these structures. Parathyroid cancer is treated first with surgery, but because it can come back in the neck, radiation has an important supporting role. Given after surgery, it targets any cancer cells left behind to lower the chance of local return, especially when the tumor had grown into nearby tissue. Radiation can also help control the cancer when it cannot be fully removed and can relieve symptoms from deposits elsewhere, such as in bone. Treatments are painless and brief, given over a series of short daily sessions. Side effects depend on the area treated and are usually temporary, such as fatigue, mild skin irritation, or a sore throat that eases after treatment.

The ways we can treat it.

Post-surgery (adjuvant) radiation. Targeted radiation to the neck after surgery treats any microscopic cancer left behind to lower the chance of local return, planned to protect the voice box, airway, and swallowing.

Definitive radiation. When surgery cannot fully remove the cancer, focused radiation helps control it in the neck.

Palliative radiation. Precise radiation aimed at painful or troublesome deposits, such as in bone, relieves symptoms and improves comfort.

Questions we hear often.

Why is my calcium so important? Parathyroid cancer usually makes too much parathyroid hormone, which drives blood calcium very high. That high calcium often causes more immediate symptoms — tiredness, thirst, kidney stones, confusion — than the tumor itself, so controlling it is a key part of treatment alongside removing the cancer.

Is surgery enough? Complete surgery is the main treatment and offers the best chance of cure. In higher-risk situations — for example when the cancer grew into nearby tissue — radiation may be added afterward to lower the chance it returns. Your team will advise based on what they find.

Will the cancer come back? Parathyroid cancer can return, sometimes years later, which is why long-term follow-up with calcium and hormone blood tests is so important. If it does return, surgery, radiation, and calcium-lowering medicines can help control it and keep you well.

This guide is informational only. It is not medical advice — please confirm anything here with your care team.