Abstract
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Objectives The aim of this study was to investigate the long-term outcomes of only lung metastasis in differentiated thyroid cancer (DTC) patients and the prognostic factors.
Methods We retrospectively reviewed 110 DTC patients (M:F=31:79, Age;46±16) with only lung metastasis from 1988 to 2014; the median follow-up was 12.6 years. Patients were treated with radioactive iodine (RAI) after total thyroidectomy. Prognostic factors for overall survival were analyzed using Kaplan-Meier method and Cox proportional-hazard regression model.
Results Of these 110 patients, 79 patients (71.8%) survived, and 31 patients (28.2%) were dead. Survival rates of 10- and 20- years were 72.4%, 67.3%. In univariate analysis, older age at diagnosis (≥45 years) (p=0.0002), less than 3 times of RAI (p=0.003), external radiotherapy (p=0.02), surgical treatment combined with external radiotherapy (p=0.02), iodine-avid with no improvement in whole body scan (WBS) (p=0.0008), and no uptake or multiple lung uptakes in WBS (p=0.03) showed poor prognosis for overall survival. In the multivariate analysis, older age at diagnosis (≥45 years) (hazard ratio [HR] 3.4, 95% confidence interval [CI] 1.2-9.4, p=0.02), less than 3 times of RAI (HR=2.8, 95% CI 1.2-6.7, p=0.02), and iodine-avid with no improvement in WBS (HR=4.8, CI 1.1-2.2, p=0.04) showed poor prognosis for overall survival.
Conclusions Older age at diagnosis, less than 3 times of RAI, and iodine-avid with no improvement in WBS were prognostic factors for poor overall survival in DTC with only lung metastasis. RAI and WBS uptake assessment are essential for the treatment of DTC with lung metastasis.