Re-treatment With Adjuvant Radioactive Iodine Does Not Improve Recurrence-Free Survival of Patients With Differentiated Thyroid Cancer

Introduction: Despite initial thyroidectomy and radioactive iodine therapy (RAI) for patients with differentiated thyroid cancer (DTC), persistent or recurrent loco regional disease is frequent. The aim was to analyze the impact of a complenetary adjuvant RAI (Ad-RAI) on disease recurrence in patients re-operated for a locally persistent or recurrent DTC. Patients and methods: Retrospective study of 85 patients with DTC, initially treated with total thyroidectomy and RAI, and re-operated for a locally persistent or recurrent disease. Propensity score was calculated to predict the impact of Ad-RAI on survival, and to reduce the bias of the limited number of patients and the prognostic tests. Results: 49 (58%) patients were re-treated with Ad-RAI after re-operation while 36 (42%) were followed up. Disease recurrence after re-management (re-operation+/-Ad-RAI) was detected in 31 patients (36.5%). In multivariate analysis, age >55 years (HR:3.9 [1.6;9.5];p30µg/l. These parameters were incorporated to calculate the Propensity score. If adjuvant RAI tended to improve the recurrence-free survival (median survival 17.4 vs 10.9 months), adjustment using Propensity score removed any difference between the groups (p=0.54), confirming the limited value of adjuvant RAI. Conclusion: In patients with locally persistent or recurrent DTC, age is the main independent prognostic factor. Adjuvant RAI does not improve the recurrence-free survival.