Radioiodine Therapy in Differentiated Thyroid Carcinoma

Abstract

Radioactive iodine [RAI] has been used in the management of patients with differentiated thyroid cancer for over 70 years. During this period, the role of RAI has evolved from treatment of metastatic disease only to include ablation of thyroid remnant tissue following total or near-total thyroidectomy. Along the way, it became apparent that patients who received RAI ablation had fewer recurrences than patients managed with thyroid hormone replacement therapy only, assigning an additional role to RAI, i.e., administration as adjuvant therapy. Currently, based on the long-term outcome experience in patients receiving ablative doses of RAI, physicians involved in the utilization of RAI are reexamining its role as an adjuvant therapy. Thus, at the present time, the decision as to ablate or not to ablate remnant tissue (and hence to forgo an adjuvant role) in patients with minimal disease and few risk factors is undergoing revision. In addition, advances in imaging instrumentation (gamma camera, SPECT, SPECT/CT, and PET/CT) and radionuclide production (I-123, I-124, F-18 FDG), available pharmacologic agents (recombinant human TSH and tyrosine kinase inhibitors), and laboratory testing (serum TSH and thyroglobulin) provide many options in terms of management. Hence, the role and utilization of RAI have become increasingly complex. This review presents the highlights of the present knowledge and understanding of the role of RAI in differentiated thyroid cancer. The reader is encouraged to investigate the many references provided as well as chapters in this compendium dealing with some aspects in more detail.