Definition of Thyroid cancer:

Thyroid cancer is a cancer that starts in the thyroid gland. The thyroid gland is located inside the front of your lower neck.

Causes, incidence, and risk factors:

Thyroid cancer can occur in all age groups.

People who have had radiation therapy to the neck are at higher risk. Radiation therapy was commonly used in the 1950s to treat enlarged thymus glands, adenoids and tonsils, and skin disorders. People who received radiation therapy as children are at increased risk for developing thyroid cancer.

Other risk factors are a family history of thyroid cancer and chronic goiter.

There are several types of thyroid cancer:

• Anaplastic carcinoma (also called giant and spindle cell cancer) is the most dangerous form of thyroid cancer. It is rare, and does not respond to radioiodine therapy. Anaplastic carcinoma spreads quickly.
• Follicular carcinoma accounts for about 10% of all cases and is more likely to come back and spread.
• Medullary carcinoma is a cancer of nonthyroid cells that are normally present in the thyroid gland. This form of the thyroid cancer tends to occur in families. It has been linked with several specific genetic mutations. It requires different treatment than other types of thyroid cancer.
• Papillary carcinoma is the most common type, and usually affects women of childbearing age. It spreads slowly and is the least dangerous type of thyroid cancer.