Radioactive iodine ablation post differentiated thyroid cancer surgery: an analysis of use and impact of the American Thyroid Association guidelines

BACKGROUND: The 2009 American Thyroid Association (ATA) three-tiered risk stratification, and its updated version in 2015, provided clearer guidance on the use of radioactive iodine (RAI) ablation in differentiated thyroid cancer (DTC) patients. This study examines the impact of these guidelines on RAI use in our institution. METHODS: Patients diagnosed with DTC during three different time periods (group 1: 2002-2006, group 2: 2010-2014 and group 3: 2017-2018) were identified and risk stratified according to the ATA guidelines. RAI use and extent of surgery were compared between the three groups. Categorical variables were analysed using Fisher's exact (2 × 2) and chi-squared (>2 × 2) tests. RESULTS: A total of 415 patients were included (group 1 = 88, group 2 = 215, group 3 = 112). The proportion of patients having total thyroidectomy were 84.6, 84.7 and 69.6% in groups 1, 2 and 3, respectively (P = 0.003). Central lymph node dissection was significantly higher in the more contemporary groups compared to group 1 (9.1 versus 41.9 versus 64.3%, P < 0.001). Overall, fewer patients received RAI in more recent times (76.6 versus 54.8 versus 26.8%, P < 0.001), most evident in the low-risk patients (70 versus 29.1 versus 5.1%, P < 0.001). In the high risk group, the majority received RAI, with no difference between the groups. CONCLUSION: Comparing DTC patients treated in our unit before and after publications of the 2009 and 2015 ATA guidelines, more nodal surgery was performed with less RAI administered in the latter groups. Better risk stratification according to the ATA guidelines has allowed more judicious use of RAI ablation.