Definition of Medullary carcinoma of thyroid:

Medullary carcinoma of the thyroid is cancer of the thyroid gland that starts in cells that release a hormone called calcitonin. Such cells are called "C" cells.

Causes, incidence, and risk factors:

The cause is unknown. Unlike other types of thyroid cancer, medullary carcinoma of the thyroid (MTC) is believed to be related to radiation therapy (a type of cancer treatment).

There are two forms of MTC:

• Sporadic MTC does not run in families. Most MTCs are sporadic. This form mainly affects older adults.
• Inherited MTC runs in families.

You have an increased risk of medullary carcinoma of the thyroid if you have:

• A family history of multiple endocrine neoplasia (MEN).
• A prior history of pheochromocytoma, mucosal neuromas, or hyperparathyroidism.

Other types of thyroid cancer include:

• Anaplastic carcinoma of the thyroid.
• Follicular tumor of the thyroid.
• Papillary carcinoma of the thyroid.
• Thyroid lymphoma.