The treatment of thyroid cancer is evolving. The molecular mechanisms of carcinogenesis for many thyroid cancers have been investigated, and have yielded targets for potential therapies. These targets include VEGFR in the treatment of all thyroid cancers, BRAF in the treatment of papillary thyroid cancer, and RET in the treatment of medullary thyroid cancer (MTC). Many promising drugs that target one or more of these proteins are currently being evaluated, including sorafenib and sunitinib, both of which are still under development for the treatment of thyroid cancer but which have been approved for use in other malignancies. In addition, compounds such as vandetanib (AstraZeneca plc) and XL-184 (Bristol-Myers Squibb Co/Exelixis Inc) have demonstrated activity in early-phase clinical trials of MTC and are being tested further in randomized trials.