Thyroid cancer is cancer of the thyroid gland. These may be of many types including papillary, follicular, Hurthle cell (aka oxyphilic or oncocytic), or medullary cancers. Surgery plays an important role in treating these cancers. The thyroid concentrates iodine and so is extremely sensitive to the effects of various radioactive isotopes of iodine produced by nuclear fission. These radioactive isotopes increase the chances of developing cancer, though thyroid cancer can develop even without any exposure to radioactivity. Some evidence suggests that insufficient or excessive dietary iodine may also increase the risk for thyroid cancer. This book presents the latest research in this field.