Prognostic factors and the effect of radioiodine on patients with locally advanced differentiated thyroid cancer

BACKGROUND: Locally advanced differentiated thyroid cancer (DTC) is rare. The optimal treatment remains controversial. This study was to investigate the natural history and prognostic factors of patients with locally advanced DTC and assess the effects of radioiodine therapy for locally advanced DTC. METHODS: A retrospective study was performed in 259 patients with locally advanced DTC. The clinicopathological features, prognostic factors and the effects of radioiodine therapy were evaluated using univariate and multivariate statistical analysis. RESULTS: Among the clinicopathological characteristics of locally advanced DTC, the patient’s age (unfavourable >55 years), extent of primary tumour (more widely extrathyroidal extension showed a worse prognosis than others), tumor size, histopathological classifications and distant metastases were the significant prognostic factors. With regard to the effects of RAI on local invasive DTC, neither T3b nor T4 patients without distant metastases could benefit from performance of (131)I therapy for over survival and locoregional relapse-free survival. CONCLUSIONS: In patients with locally advanced DTC, the independent prognostic factors were age, extent of extrathyroidal invasion, tumor size, histopathological classifications and distant metastases. Adjuvant postoperative RAI did not affect overall survival and locoregional control in patients with locally advanced DTC who had no distant metastasis disease. Given the results, we suggested radioiodine would not be applied for metastasis-free patients with locally advanced DTC postoperatively.