Pulmonary metastases in differentiated thyroid cancer: efficacy of radioiodine therapy and prognostic factors

Abstract

ContextData from a large cohort of patients with pulmonary metastases from differentiated thyroid cancer (DTC) were retrospectively analyzed.ObjectiveTo assess the effect of radioiodine therapy and investigate the prognostic factors of survival for patients with pulmonary metastasis secondary to DTC.MethodsA total of 372 patients with pulmonary metastasis from DTC treated with131I entered the study. According to the results of131I whole-body scan (WBS), pulmonary metastases were classified as131I-avid and non-131I-avid. For patients with131I-avid lung metastases, treatment response was measured by three parameters: serum thyroglobulin (Tg) levels, chest computed tomography (CT) and post-therapeutic131I-WBS. Overall survival was calculated by the Kaplan–Meier method. Factors predictive of the outcome were determined by multivariate analyses.ResultsAmong patients demonstrating131I-avid pulmonary metastases (256/372, 68.8%), 156 cases (156/256, 60.9%) showed a significant decrease in serum Tg levels after131I therapy and 138 cases (138/229, 60.3%) showed a reduction in pulmonary metastases on follow-up CT. A complete cure, however, was only achieved in 62 cases (62/256, 24.2%). Multivariate analysis showed that only age, the presence of multiple distant metastases and pulmonary metastatic node size were significant independent variables between the groups of131I-avid and non-131I-avid.ConclusionThis study indicated that, most131I-avid pulmonary metastases from DTC can obtain partial or complete remission after131I therapy. Younger patients (<40 years old) with only pulmonary metastases and small (‘fine miliaric’ or micronodular) metastases appear to have relative favorite outcomes. Patients who do not respond to131I treatment have a worse prognosis.