Variations in Radioiodine Therapy in Europe: Decision-Making after Total Thyroidectomy.

The role of radioiodine therapy (RIT) (used as ablation therapy or adjuvant therapy) following total thyroidectomy for differentiated thyroid cancer (DTC) changed. Major revisions of the American Thyroid Association (ATA) Guidelines in 2015 resulted in significant differences in treatment recommendations in comparison to the European Association of Nuclear Medicine (EANM) 2008 guidelines. Recently, we presented the effects on daily practice for RIT among Swiss Nuclear Medicine centres. We now performed a study at the European level and hypothesized that there is also considerable variability among European experts. We performed a decision-tree-based analysis of management strategies from all members of the EANM thyroid committee to map current practice among experts. We collected data on whether or not RIT is administered, on which criteria these decisions are based and collected details on treatment activities and patient preparation. Our study shows discrepancies for low-risk DTC, where "follow-up only" is recommended by some experts, while RIT with significant doses is used by other experts. E.g., for pT1b tumours without evidence of metastases, the level of agreement for the use of RIT is as low as 50%. If RIT is administered, activities of I-131 range from 1.1 GBq to 3.0 GBq. In other constellations (e.g., pT1a), experts diverge from current clinical guidelines as up to 75% administer RIT in certain cases. For intermediate and high-risk patients, RIT is generally recommended. However, dosing and treatment preparation (rhTSH vs. thyroid hormone withdrawal) vary distinctly. In comparison to the Swiss study, the general level of agreement is higher among the European experts. The recently proposed approach on the use of RIT, based on integrated post-surgery assessment (Martinique article) and results of ongoing prospective randomized studies are likely to reduce uncertainty in approaching RIT treatment. In certain constellations, consensus identified among European experts might be helpful in formulating future guidelines