Chapter 8: Management of Radioiodine Refractory Thyroid Cancer

A small subset of patients with differentiated thyroid cancers (DTCs), over the course of their natural disease progression, undergo dedifferentiation which leads to altered tumor biology and an inability to concentrate and respond to radioactive iodine (RAI), despite being able to functionally produce and release thyroglobulin. They broadly consist of two groups - (a) thyroglobulin-elevated negative iodine scintigraphy and (b) radioiodine refractory DTC. This review deals with their definitions, presentation, and overall management principles, highlighting the key points of their treatment philosophy. Whole-body 18F positron emission tomography-computed tomography is the investigation of choice since majority of these become fludeoxyglucose avid once they lose their iodine avidity. Asymptomatic patients with low disease burden may be observed. Surgical ablation, for symptomatic patients with accessible disease is the prime treatment modality. For those deemed inoperable with high tumor burden and increasing symptomatology are best treated with multikinase inhibitors. External beam Radiation may be a choice for painful bony metastasis, while those refractory to multikinase inhibitors may be offered newer forms of localized therapy such as radiofrequency ablation, newer isotope therapy, and transarterial chemoembolization.