241 Predictors of Post-Radioiodine Ablation Outcomes in Thyroid Cancer: Analysis of Four Years of Data from a Regional Centre

Aim To assess correlations between patient demographics, tumour and lymph node pathology and outcomes for patients with non-metastatic thyroid cancer. Outcomes examined were evidence of post-ablation residual disease on blood testing or ultrasound or thyroid cancer recurrence. Method Electronic records for thyroid cancer patients at a regional centre undergoing thyroidectomy followed by Radioiodine-131 ablation in the years 2018-2021 were reviewed with 191 records contributing to the analysis. Patient demographics, tumour characteristics, numbers of positive lymph nodes and radioiodine dosages were compared against patient outcomes. Results Increasing age, T stage of the tumour and lymph node involvement demonstrated the strongest correlations with negative outcomes. Age appeared to be a strong risk factor for thyroid cancer recurrence with 70% of the patient’s experiencing recurrence aged over 60 despite patients over 60 making up only 33% of the sample. Removal of over 4 metastatic lymph nodes has previously been found to predict poorer patient outcomes. The findings support this however over 50% of positive nodes removed had a stronger correlation with negative outcomes compared with raw numbers retrieved. 52.2% of patients with over 50% positive lymph nodes experienced poorer outcomes compared with 40.1% who had over 4 positive nodes removed. The correlation was stronger still for those with over 4 positive nodes of which over 50% were positive of whom 57.9% demonstrated poor outcomes. Conclusions Rather than raw numbers of lymph nodes removed, proportion of metastatic nodes of those harvested or a combination of total numbers and proportion appeared to give a better indicator of prognosis.