ON THIS PAGE: You will find some basic information about this disease and the parts of the body it may affect. This is the first page of Cancer.Net’s Guide to Parathyroid Cancer. To see other pages, use the menu on the side of your screen. Think of that menu as a roadmap to this full guide.
About the parathyroid glands
The parathyroid glands are four small glands located near the thyroid gland in the neck or chest, which is also called the upper mediastinum. They are part of the endocrine system. Like all parts of the endocrine system, the parathyroid glands play an important role regulating hormones in the body. These glands make parathyroid hormone (PTH), which regulates the levels of calcium and phosphorus in the blood.
About parathyroid cancer
Cancer begins when normal cells change and grow uncontrollably, forming a mass called a tumor. A tumor can be cancerous or benign. A cancerous tumor is malignant, meaning it can spread to other parts of the body. A benign tumor means the tumor will not spread. A parathyroid tumor usually develops in one of the four parathyroid glands.
A parathyroid tumor, whether it is benign or malignant, can cause significant effects because the amount of calcium in the blood rises, resulting in a serious condition called hypercalcemia .
This section covers tumors found in the parathyroid glands. Learn more about tumors that begin in the thyroid gland  in a separate section.
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