Medullary thyroid cancer (MTC) is a rare type of thyroid cancer. It is often slow-growing.
MTC starts in cells in the thyroid gland called parafollicular cells or C cells. These cells normally make a hormone called calcitonin, which helps control the level of calcium in the blood.
About 5 to 9 out of 100 (5 to 9%) of thyroid cancers are MTC.
MTC may develop in people who have a rare inherited condition called multiple endocrine neoplasia (MEN).
We also have information about other types of thyroid cancer, including follicular, papillary and anaplastic thyroid cancer, and thyroid lymphoma.