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 colored boxes on the right side of your screen. Think of those boxes as a roadmap to this full guide. Or, click “Next” at the bottom of each page.
About the parathyroid glands
The parathyroid glands are four small glands located in the neck or upper mediastinum (chest) near the thyroid gland. 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 benign (noncancerous) or malignant (cancerous, meaning it can spread to other parts of the body). 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.
Choose “Next” (below, right) to continue reading this detailed section. To select a specific topic within this section, use the colored boxes located on the right side of your screen.