The thyroid is a butterfly-shaped gland located in the neck, below the Adam's apple.
Hormones made by the thyroid are also important during childhood growth and development.
The thyroid uses iodine, a mineral found in iodized salt and in some foods, to make several of its hormones. Thyroid cancer is a disease in which thyroid cells become abnormal, grow out of control, and form a cancerous tumor. If left untreated, thyroid cancer can spread to other parts of the body through a process called metastasis. In 1997 an estimated 16,100 people in the United States will be diagnosed with thyroid cancer. This disease, which is the most common cancer of the endocrine system, accounts for about 1 percent of all cancers.