Metastatic differentiated thyroid carcinoma: clinical management and outcome of disease in patients with initial and late distant metastases

OBJECTIVE: Our objective was to analyze the clinical management and the outcome of disease in differentiated thyroid carcinoma with initial and late distant metastases (M1). PATIENTS AND METHODS: Radioiodine (131I) therapy was applied in 77 differentiated thyroid carcinoma patients with M1 (31 patients with M1-initial and 46 patients with M1-late). The median follow-up of patients was 72.7 months. Probability of disease-specific survival (DSS) was analyzed by the Kaplan-Meier method and the log rank test, while the significance of differences between groups was calculated by the t-test of proportions. RESULTS: Follicular carcinomas were more frequent in patients with M1-late (P<0.05). During the follow-up, 58% of the patients died: 39% of cases had disease related deaths, while 42% had complete remission of disease. Stable disease and progressive disease were significantly influenced by age only (P = 0.0122), while 131I uptake, histological type, and sex had no influence (P = 0.1235; P = 0.340; P = 0.8540, respectively). Remission of disease (complete and partial) was not significantly influenced by age, sex, histological type, and 131I accumulation (P = 0.0644; P = 0.8452; P = 0.6308; P = 0.7675, respectively). DSS in patients with M1-initial and M1-late at 5 years was 71 and 50%, respectively and 62 and 41% at 10 years, respectively, without significant difference (P = 0.2582). Disease related deaths appeared more frequent in patients at 45 years of age or older, significantly caused by distant metastases (P<0.001). CONCLUSION: Distant metastases occur late more often in patients with follicular carcinoma while M1-initial is detected more often in patients with papillary carcinoma. DSS was not significantly different among patients with M1-initial and M1-late. The risk of death from M1 increased after the age of 45 years.