Background: The aim of this study was to identify the prognostic factors of long-term survival and optimal therapeutic protocol for patients with distant metastasis secondary to differentiated thyroid carcinoma (DTC).
Methods: A retrospective review of 1665 patients with DTC treated at a regional tertiary hospital in Taiwan between 1986 and 2010 was performed. Among them, 207 patients were found to have distant metastasis. For a long-term outcome survey, 126 patients that had received at least 5 years (mean 9·6 ± 5·2 years) of follow-up after the diagnosis of distant metastasis were analysed for this study. Prognostic factor analysis included age, sex, histology, disease stage, type of surgical procedure, site of metastatic foci, (131) I avidity of tumour, thyroglobulin (Tg) level and accumulated therapeutic dose of radioiodine (RAI).
Results: The mean age at diagnosis of distant metastasis was 46·4 ± 17·2 years. The female-to-male ratio was 2·1:1. The 10- and 15-year survival rates were 70·6% and 64·9%, respectively. The independent predictors of survival were younger age, surgical dissection of neck lymph nodes (LNs) and low TSH-stimulated Tg level (<400 μg/l) at the discovery of metastasis. Most cases of resolved (131) I-avid disease (79·2%) and disease-free remission (87·5%) received a cumulative dose no >600 mCi of (131) I. The mean cumulative doses of (131) I in both deceased and living patients were similar.
Conclusion: The prognosis of patients with distant metastasis from DTC within this study was found to be favourable. Survival may be improved by surgical dissection of neck LNs, but repeated (131) I therapy >600 mCi is not advised unless there is a high probability that it would benefit the patient.
© 2012 Blackwell Publishing Ltd.