MEDICAL ANIMATION TRANSCRIPT: Thyroid cancer is a disease that begins in your thyroid gland. Your thyroid gland is located over your larynx or voice box. It wraps around your trachea or windpipe. Your thyroid produces two hormones called thyroid hormone and calcitonin and secretes them directly into your bloodstream. Inside your thyroid gland follicular cells make thyroid hormone. Your body uses thyroid hormone to increase your energy and raise your body temperature when necessary. For example these effects help offset the heat your body loses when exposed to cold weather. Parafollicular cells in your thyroid make calcitonin. Calcitonin is thought to stimulate the formation of new bone. If you have thyroid cancer it may be one of four types, depending on the type of thyroid cell in which the cancer started and the appearance of the cancer cells. Papillary carcinoma is the most common thyroid cancer and begins in follicular cells. Follicular carcinoma accounts for 1 in 10 cases and also begins in follicular cells. Medullary carcinoma is less common and starts in parafollicular cells. Anaplastic thyroid carcinoma is a rare more dangerous form of thyroid cancer. Thyroid cancer like all cancers is an unrestrained growth of cells due to damaged genetic material in the cell's nucleus. A tumor forms as the cells begin to accumulate. Over time a lump forms in your thyroid as the tumor enlarges. You may feel a lump in your neck over the thyroid gland. You may have neck or throat pain, hoarseness, and trouble swallowing as the tumor grows around your trachea. To treat thyroid cancer your doctor may recommend surgery followed by thyroid hormone therapy, radiation therapy, or chemotherapy. Surgery is the most common treatment for all types of thyroid cancer. If you have surgery your doctor will usually remove your entire thyroid gland. Your doctor may remove nearby lymph nodes as well. After surgery your doctor may recommend thyroid hormone therapy. Without your thyroid your body will have low levels of thyroid hormone. This condition stimulates the pituitary gland in your brain to release thyroid stimulating hormone. Increased levels of thyroid stimulating hormone cause any remaining thyroid cancer cells to grow faster. If you take thyroid hormone it will reduce the amount of thyroid stimulating hormone circulating in your body, which will prevent the cancer cells from growing. If you have anaplastic thyroid cancer and have already had surgery, your doctor may recommend radiation therapy such as external beam radiation therapy. Radiation damages and kills any remaining thyroid cancer cells. After surgery your doctor may give you a pill containing another type of radiation therapy called radioactive iodine. Any remaining thyroid cancer cells absorb the radioactive iodine which kills them. Your doctor may recommend chemotherapy therapy for anaplastic thyroid cancer that does not respond to surgery or radiation and has spread. Chemotherapy uses drugs to stop the progression of cancer by either killing the cancer cells or preventing further growth.