Trends in metastatic thyroid cancer survival from 1992 to 2022: a SEER database analysis

The majority of thyroid cancers present as localized disease that is treated with surgery or radioactive iodine. Despite the effectiveness of radioactive iodine, 5-10% of thyroid cancers are radioiodine-resistant and are termed radioiodine-refractory (RAIR) thyroid cancers. RAIR tumors that spread distantly exhibit high mortality. Phase III trials, in the early 2010s, for tyrosine kinase inhibitors (TKIs) such as lenvatinib, sorafenib, and cabozantinib have shown promise in extending progression-free survival (PFS) in patients with RAIR, but it remains unclear whether these advances have improved disease-specific survival (DSS). We conducted a survival analysis of metastatic thyroid cancers using the Surveillance, Epidemiology, and End Results (SEER) national database to assess changes in DSS from 1992 to 2022. Patients were divided into three cohorts based on the year of diagnosis: 1992-2001, 2002-2011, and 2012-2022. Kaplan-Meier and Cox regression analyses were used to assess survival trends and effects of demographic and treatment variables. Our results suggest a modest but significant improvement in DSS for those diagnosed with distant metastasis of anaplastic, follicular, medullary, and oncocytic thyroid carcinoma in the most recent decade (2012-2022) compared to earlier periods. Limited information on detailed treatment data, imposed by the use of SEER, ought to be considered. Future studies with more detailed treatment data would be beneficial for confirming our findings and better characterizing RAIR thyroid cancer survival.