Risk Factor Stratification of Lung Metastasis in Children and Adolescent Papillary Thyroid Cancer

Background: Lung metastasis (LM) in pediatric papillary thyroid cancer (pPTC) is significantly higher than in adults. While spare information about pPTC and LM hampers to formulate specific guideline. Hence, we retrospectively analyzed the whole pPTCs in our center to investigate factors associated with LM and therapy outcomes. Materials: and Methods: PTCs with age＜20 years who received initial operations in ourcenterfrom December 2008 to December 2018 were retrospectively reviewed. Clinicopathological information, treatment pipelineand outcomes were analyzed retrospectively. Results: : Totally, 114 pPTC patients were enrolled in our study, LM was observed in 17 (14.9 %) cases. Significant risk factors associated with LM were age, sex, tumor size, multifocality, extrathyroidal extension, lymph node metastasis, number of metastatic lymph nodes (NMLNs)and postoperative stimulated thyroglobulin (sTg). NMLNs ＞14 was identified as an independent risk factor for LM by multivariate analysis (OR 25.166, 95% CI 2.814 - 225.009, p = 0.004) with a sensitivity of 86.7% and specificity of 81.1% for LM, which was verified by integrated meta-analysis. In terms ofresponse to radioiodine treatment in LM, 2 cases reached ‘‘excellent’’ response. ‘‘Biochemically incomplete’’, ‘‘structurally incomplete’’ and “indeterminate” were in 3,12, 2 of 17 patients respectively. Postoperative sTg was correlated with the response to therapy of LM in pPTCs( p = 0.003). Conclusion: LM was frequently observed in pPTCs. NMLNs ＞14 was an independent risk factor for LM in our study and other cohorts, and postoperative sTg was a potential predictor for the therapy outcome of LM in pPTCs.