Clinical outcome and influencing factors of differentiated thyroid cancer patients with radioiodine-refractory lung metastasis.

[PURPOSE] A subset of patients with differentiated thyroid cancer and lung metastases (DTC-LM) may progress to radioiodine-refractory (RAIR) disease, which is associated with a poor prognosis. This study aimed to investigate the clinical outcomes and potential risk factors associated with RAIR disease in DTC-LM patients.

[METHODS] 177 DTC-LM patients who underwent radioiodine (RAI) therapy at our center were retrospectively analyzed. Clinicopathological profiles were compared between the RAI-avid (RAIA) and RAIR groups. Univariate and multivariate regression analyses were conducted to identify risk factors for RAIR status and progressive disease (PD).

[RESULTS] Overall, 80 patients were included in the RAIR group, accounting for 45.2% of the total patients. Multivariate analysis revealed that older age and higher T stage were independent risk factors for RAIR disease. Age≥55 years (HR: 2.975, 95% CI: 1.424 -6.218, P = 0.004), RAI-avid status (HR: 4.315, 95% CI: 1.753 - 10.622, P = 0.001) and the ps-Tg≥528.5ng/mL (HR: 3.665, 95% CI: 1.656 - 8.107, P = 0.001)were identified as independent predictors of PD. Kaplan-Meier analysis revealed a lower progression-free survival (PFS) rate in the RAIR group than in the RAIA group (P< 0.001).

[CONCLUSION] RAIR disease is common among DTC-LM patients and is associated with adverse clinical outcomes. Age, RAI avidity status, and ps-Tg levels serve as important predictors of PD. Early risk stratification and individualized management strategies are crucial to improving outcomes in DTC-LM patients.