Strategies for Radioiodine Treatment: What's New

Abstract

Radioiodine treatment (RAI) represents the most widespread and effective therapy for differentiated thyroid cancer (DTC). RAI goals encompass ablative (destruction of thyroid remnants, to enhance thyroglobulin predictive value), adjuvant (destruction of microscopic disease to reduce recurrences), and therapeutic (in case of macroscopic iodine avid lesions) purposes, but its use has evolved over time. Randomized trial results have enabled the refinement of RAI indications, moving from a standardized practice to a tailored approach. In most cases, low-risk patients may safely avoid RAI, but where necessary, a simplified protocol, based on lower iodine activities and human recombinant TSH preparation, proved to be just as effective, reducing overtreatment or useless impairment of quality of life. In pediatric DTC, RAI treatments may allow tumor healing even at the advanced stages. Finally, new challenges have arisen with the advancement in redifferentiation protocols, through which RAI still represents a leading therapy, even in former iodine refractory cases. RAI therapy is usually well-tolerated at low activities rates, but some concerns exist concerning higher cumulative doses and long-term outcomes. Despite these achievements, several issues still need to be addressed in terms of RAI indications and protocols, heading toward the RAI strategy of the future.

Keywords: overtreatment; quality of life; radioiodine; redifferentiation; risk assessment; thyroid cancer.

Figure 1

Indications for RAI therapy considering both dynamic risk assessment and ¹⁸FDG-PET information. Abbreviations: RAI, radioiodine; ATA, American Thyroid Association; FDG-PET, fluorodeoxyglucose-positron emission tomography; Tg, thyroglobulin; rhTSH, human recombinant thyroid stimulating hormone; THW, thyroid hormone withdrawal; ER, excellent response; SIR, structural incomplete response; BIR, biochemical incomplete response; IndR, indeterminate response.