Radioactive iodine therapy

Follicular and papillary thyroid cancers are sometimes treated with radioactive iodine (RAI) therapy. RAI therapy may be given to children after surgery to kill any thyroid cancer cells that were not removed or to children whose tumor cannot be removed by surgery. RAI is taken by mouth and collects in any remaining thyroid tissue, including thyroid cancer cells that have spread to other places in the body. Because only thyroid tissue takes up iodine, the RAI destroys thyroid tissue and thyroid cancer cells without harming other tissue. Before a full treatment dose of RAI is given, a small test dose is given to see if the tumor takes up the iodine.