Referral Practice for Radioactive Iodine Ablation (RAI) after ATA guidelines 2015: results from a Tertiary Cancer Care Centre

Introduction The ATA guidelines for differentiated thyroid cancer (DTC) are one of the most widely referred to. Their 2015 edition proposed a new risk stratification system and modified the indications for radioactive iodine (RAI) ablation especially for the low risk category. We attempted to analyze whether the new guidelines altered referral practices for RAI ablation at our institute. Methodology Patients who underwent total or completion thyroidectomy for DTC during 2016-2017 were included. Relevant demographical and pathological data was tabulated. Patients were classified as per the new stratification system and referral practice for RAI ablation documented. Results 238 patients were included. Of these 20.6% were low risk, 44.1% were intermediate and 35.3% were high risk as per modified guidelines. All patients within the intermediate and high-risk group and 77.8% of the low risk group were referred for RAI ablation. Analysis of risk factors revealed that within the low risk group there were three patients with < 5 metastatic nodes, all within 3 cm in size-a category that the ATA failed to stratify appropriately. Among those labeled as Intermediate risk due to microscopic extra thyroidal extension (ETE), 85% had no other risk factors and were upstaged solely due to microscopic ETE, which is interestingly no longer included in the TNM staging. Conclusion Majority of low risk patients continue to receive RAI ablation due to persistent belief emanating from literature that remnant ablation improves outcomes and aids in follow up. The issue of RAI ablation for low risk group and prognostic implications of microscopic ETE and limited nodal disease need to be revisited.