Disease-specific Mortality of Differentiated Thyroid Cancer With Distant Metastases

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.

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.

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).

DM from DTC are associated with ∼ 55% mortality at a median survival of 47 months. Increasing age and skeletal metastases are predictors of an increased risk of mortality.