Papillary thyroid carcinoma (PTC) with pulmonary metastases is rare in children and adolescents. Unlike adults, limited data are available on children with this disease. Thus, this study evaluated the therapeutic efficacy and prognostic factors of individuals less than 21 years of age with pulmonary metastases from PTC.

Seventy-six children and adolescents with pulmonary metastases from PTC treated with ¹³¹I were retrospectively analyzed. Therapeutic efficacy was evaluated by changes in serum thyroglobulin (Tg) and chest computed tomography (CT). Factors predictive of progression-free survival and overall survival were measured by the Kaplan-Meier method.

Among the 76 patients included in this study, 22.4% (17 of 76) were less than 15 years old and 65.8% (50 of 76) were female. Under the evaluation of stimulated serum Tg levels, RAI treatment were effective in 55.9% (38 of 68), stable in 26.5% (18 of 68) and ineffectvie in 17.6% (12 of 68) of patients. Changes on anatomical imaging suggested complete response (CR), partial response (PR), stable disease (SD) and progressive disease (PD) in 8.5, 62.0, 15.5, and 14.1% of individuals, respectively. Univariate analysis showed that size and tumor doubling time of pulmonary metastases were independent factors affecting therapeutic efficacy. Extra-thyroidal extension, tumor diameter of pulmonary metastases and tumor doubling time were significant independent factors regarding progression-free survival rates, while only tumor doubling time and tumor diameter were significant risk factors associated with overall survival rate.

Radioactive iodine therapy is an effective treatment for children and adolescents with pulmonary metastases from PTC. Extra-thyroid extension was associated with disease progression while did not show significant influence on overall survival. Tumor doubling time and tumor diameter were the main factors influencing both progression-free survival and overall survival.