Treatment of iodine refractory well differentiated thyroid carcinoma: Real world data from a tertiary center in Mexico.

e18064 Background: Sorafenib and lenvatinib are the only drugs approved based on phase III clinical trials as first-line treatment in radiation-refractory, progressive, differentiated thyroid carcinoma, with limited data available for a direct comparison of these tyrosine kinase inhibitors. We aimed to evaluate the progression-free survival between the two groups treated with both medications in a Mexican tertiary center. Methods: In this retrospective study conducted from December 2015 to June 2024, we evaluated the outcomes of 38 patients with metastatic/locally advanced, progressive, RAI-refractory DTC/PDTC, treated with sorafenib or lenvatinib. The primary outcome was the probability of progression-free survival (PFS) between both groups. Results: Eighteen patients treated with sorafenib and twenty patients with lenvatinib were included. The median age was 64.5 years, and 76% were women. Papillary histology was the most frequent (81%), and they were diagnosed at stage IV in the majority of cases (82%). More than half of the patients had previously undergone surgery, radiotherapy, and/or radioactive iodine treatment. After a median follow-up of 13.2 months, no difference in PFS was observed between the sorafenib and lenvatinib arms (HR 1.53, 95% CI 0.38-6.05, p=0.54). Conclusions: Sorafenib and lenvatinib have shown comparable efficacy in prolonging progression-free survival in Mexican patients with metastatic/locally advanced, progressive, RAI-refractory DTC/PDTC, leading to markedly superior outcomes compared to pivotal studies.