BACKGROUND: This study aimed to investigate the parameters influencing the effectiveness of first 131I thyroid remnant ablation and then 131I treatment of metastatic lesions in children and adolescents with differentiated thyroid carcinoma (DTC).

MATERIAL AND METHODS: A total of 88 children and adolescents with DTC were divided into 2 groups: 56 in the complete-ablation group and 32 in the incomplete-ablation group for the first 131I ablation; 32 in the incomplete-ablation group were further divided: 19 in the complete-remission group and 13 in the incomplete-remission group for subsequent 131I treatment of metastatic lesions. Influential parameters were analyzed using t test, t‘ test, rank-sum test, χ2-test, and Fisher exact test, and logistic regression analysis was performed. Radioactive iodine uptake (RAIU), lymph node metastases, and pulmonary metastases were selected as influential parameters.

RESULTS: After logistic regression analysis, RAIU, only lymph node metastases, and pulmonary metastasis were significantly associated with the complete-ablation rate. High levels of RAIU and serum thyroglobulin (Tg) were not conducive to disease remission after subsequent 131I treatment of metastatic lesions. The remission rate of patients with pulmonary metastasis was lower than the rate of patients with lymph node metastases or no metastases.

CONCLUSIONS: Results demonstrated that a high remission rate is associated with low postoperative RAIU and Tg. Lymph node metastasis and pulmonary metastasis reduce the complete-remission rate of first 131I ablation therapy. Pulmonary metastasis reduces the remission rate of subsequent 131I treatment. Also, 131I treatment for pediatric DTC with pulmonary metastasis achieved progression-free survival.

Keywords: Adolescent, Ablation Techniques - methods, Carcinoma - surgery, Child, Child, Preschool, Disease-Free Survival, Iodine Radioisotopes - therapeutic use, Thyroid Neoplasms - surgery, Thyroidectomy