Thyroid cancer is a disease that occurs when abnormal cells begin to grow in the thyroid gland. You may notice a lump in your neck and then go to your doctor. Or your doctor may notice a lump during a routine physical exam or on an imaging test that you are having for another health problem.

Thyroid cancer is usually found before the cancer has spread very far. This means that most people who are treated for thyroid cancer do very well. Treatment for thyroid cancer includes surgery, radioactive iodine treatment, thyroid hormone medicines, and in rare cases, radiation therapy or chemotherapy. After it is treated, thyroid cancer may come back, sometimes many years after treatment.

Before starting your treatment, your doctor needs to find out which of the five types of thyroid cancer you have. A biopsy can identify your type of cancer. During a biopsy, a small piece of thyroid tissue is removed, usually with a needle. The thyroid tissue cells are then examined under a microscope.

It is also important to determine the stage of your cancer. Staging is a way for your doctor to tell how far, if at all, the cancer has spread. It also helps your doctor decide what kind of treatment you need. Staging generally depends on your age and the results of tests done after you have had surgery to remove part or all of your thyroid gland. Sometimes lymph nodes in your neck may also be removed and examined to see if cancer is present.

If you have your thyroid gland surgically removed, you will probably have symptoms of hypothyroidism-a lack of thyroid hormone-and you will need to take thyroid hormone medicines for the rest of your life. These medicines help regulate your metabolism and other body functions that are normally influenced by the thyroid gland. For more information, see the topic Hypothyroidism.