Advanced differentiated thyroid cancer: when to stop radioiodine?

Radioiodine (RAI) is a pivotal important treatment for patients with metastatic differentiated thyroid cancer (DTC). In order to determine when a patient will no longer respond to RAI, multiple classifications have been described to categorize a patient as RAI refractory (RAI-R). Current classifications, although very useful, are problematic and controversial and cannot be merely applied in the context of individualized patient management. In addition, classifications on how to define RAI-R disease are continuously evolving as more studies are published and managing physicians better understand the limitations and confounding factors of present classifications. Accordingly, each patient should be individually managed with a good understanding of the limitations of the various classifications, assessing the many other factors that affect the patient's specific clinical situation and delivering appropriate individualized patient care.