Radioiodine versus no radioiodine outcomes in low‐risk differentiated thyroid cancers: A propensity‐score matched analysis

Abstract

AbstractObjectiveThe 2015 American Thyroid Association guidelines recommend against radioiodine (RAI) ablation for patients with low‐risk papillary microcarcinoma. However, its role in other low‐risk differentiated thyroid cancer (DTC) patients remains controversial. Here, we compare long‐term outcomes with RAI versus no‐RAI in a large cohort comprising all low‐risk DTCs.MethodsPatients with low‐risk, histologically‐proven DTC post‐thyroidectomy, treated with RAI or kept on follow‐up without RAI, between 1990 and 2019 were included. The main outcomes included recurrence rate and recurrence‐free survival (RFS), and were validated by propensity‐score matching analysis.ResultsOf the 2074 low‐risk DTC patients (median age: 35 years), 1686 patients underwent RAI‐ablation (RAI group), while 388 patients underwent no‐RAI follow‐up (NOI group). Over a median follow‐up of 8 years (range: 3–29), the recurrence rates were similar between the RAI and NOI groups (2.0% vs. 3.3%, p = .161). The 5‐ and 10‐year RFS probabilities were 99.2% and 97.4%, respectively in RAI group versus 98.4% and 96.2%, respectively, in NOI group (p = .055). Subgroup regression analyses showed that patients with age <55 years (p = .044), male sex (p = .015), papillary histology (p = .043), pT3a tumours (p = .049) and postoperative thyroglobulin ≥5 ng/mL (p = .002) had significantly better RFS with RAI compared to NOI follow‐up. Propensity‐score matching generated 776 matched pairs with no significantly different outcomes between the two groups.ConclusionsIn low‐risk DTC patients post‐thyroidectomy, RAI ablation does not confer significant survival advantage over no‐RAI follow‐up. Further studies are required to demonstrate any long‐term benefit with RAI, specifically in patients with tumour size >4 cm and elevated postoperative thyroglobulin.