Clinical outcomes and prognostic factors in patients with no less than three distant organ system metastases from differentiated thyroid carcinoma

Objectives For patients with differentiated thyroid carcinoma (DTC), distant metastases are commonly identified in the lungs and bones. However, they are relatively rare in other distant organs, such as the liver, kidneys, or brain. The aim of the current study was to describe the clinical outcomes and evaluate the prognostic factors of patients with no less than three different distant organ system metastases from DTC. Methods This study retrospectively identified 717 patients diagnosed with DTC with distant metastases between January 2005 and December 2017. Patient response to radioactive iodine (RAI) therapy was monitored by changes in serum thyroglobulin levels and imaging changes. Five-year and 10-year overall survival (OS) rates were calculated by the Kaplan-Meier methods and Cox proportional hazards. Results Among the 717 participants, 37 (5.16%) patients had no less than three different distant organ system metastases from DTC. Five-year and 10-year OS were 45.9% and 37.8% in patients with three or more distant organ system metastases while 74.5% and 64.9% in individuals with one or two distant organ system metastases, respectively. RAI avidity and RAIR-DTC were main independent prognostic factors influencing the clinical outcomes for both groups of patients. The presence of 3 or more different distant organ system metastases was the only independent prognostic factors for 10-year OS by multivariate analysis. Conclusions Patients with no less than three distant organ system metastases from DTC had poor prognosis. RAI avidity and RAIR-DTC were main factors influencing overall survival for patients with distant metastases from DTC in both groups.