Disease-specific Mortality of Differentiated Thyroid Cancer With Distant Metastases

Overview: Distant metastases (DM) are the major cause of death in patients with differentiated thyroid cancer (DTC). This study aimed to investigate the predictors of DM-associated mortality. Patients and Methods: We identified 154 thyroid cancer (TC) patients with DM from our institution's tumor registry. We excluded anaplastic (n = 21) and medullary TC (n = 32) and patients with inadequate data (n = 15). The remaining 86 patients with DTC were studied. These include 57 females (66.3%) and 29 males (33.7%) with a median age of 53.5 years [interquartile range (IQR) 45-65]. All patients underwent thyroidectomy; 58 (67.4%) had neck dissection, and 81 (94.2%) received radioactive iodine (I-131) ablation/therapy. Results: Lung metastases were the most common, occurring in 91.9%; skeletal metastases occurred in 58.1%, brain metastases in 9.3%, and multiple-organ DM in 58%. The management of DM included surgery, 1 or more doses of I-131, external beam radiotherapy, and multikinase inhibitors. Over a median follow-up of 84 months (IQR 35.5-118) for the whole cohort, 47 patients succumbed to their disease (disease-specific mortality 54.7%). Factors associated with mortality were increasing age (P = .001) and bone metastases (P < .0001). These factors remained significant in multivariate analyses [for age, P = .009, hazard ratio (HR) 1.030, 95% confidence interval (CI) 1.007-1.053] and for bone metastases (P = .017, HR 2.58, 95% CI 1.19-5.6). Conclusion: DM from DTC are associated with similar to 55% mortality at a median survival of 47 months. Increasing age and skeletal metastases are predictors of an increased risk of mortality.