Reacquisition of Radioactive Iodine (RAI) Uptake of RAI-Refractory Metastatic Thyroid Cancers by Pretreatment With the Selective MEK Inhibitor AZD6244

The purpose of this study is to find out if the drug AZD6244 can improve the radioactive iodine uptake by the patient's metastatic thyroid cancer. The investigator will also be testing the tumor specimen taken at the time of your surgery for specific genetic changes to see if one of them in particular (the BRAF oncogene) makes your cancer more likely to become sensitive to radioactive iodine after treatment with the drug. The investigators want to find out if AZD6244 helps to increase the entry of radioactive iodine into thyroid cancer cells that have spread and are resistant to radioactive iodine therapy, especially if they have the BRAF mutation. To measure how much iodine can enter your cancer, the investigators will use iodine-124, a different form of radioactive iodine. Iodine-124 allows the investigators to measure precisely how much radioactivity can enter the cancer cells, whereas iodine-131 does not. The process of scanning with iodine-124 is called "lesional dosimetry". Iodine-124 is an investigational agent approved by the FDA (Food and Drug Administration) for use in this research study.