Clinical outcomes and associated factors of radioiodine-131 treatment in differentiated thyroid cancer with cervical lymph node metastasis

Cervical lymph node metastasis (CLNM) is common in differentiated thyroid cancer (DTC). Radioiodine-131 (I-131) treatment is recommended for the removal of residual thyroid tissue following thyroidectomy. To date, the effect of I-131 therapy on the outcomes of patients with DTC with CLNM is unclear. The aim of the present study was to evaluate the final outcome of patients with DTC with CLNM according to I-131 administration, and to analyze the factors that may affect clinical outcomes. A total of 357 patients with DTC with CLNM were recruited and divided into three groups: Those who received 2, 3 or 4 doses of I-131 therapy, respectively. Successful ablation was defined as levels of stimulated serum thyroglobulin <2 ng/ml in the absence of CLNM. The rates of successful ablation were 80.35 (229/285), 76.36 (42/55) and 70.59% (12/17) for patients who received 2, 3 and 4 doses, respectively. The patients with DTC with CLNM who were <45 years old, with tumor sizes <2 cm, solitary nodules and TNM stage I-II disease exhibited significantly higher rates of successful ablation compared with the patients who were >= 45 years old, with tumor size >= 2 cm, multiple nodules and stage III-IV disease. Multivariate analyses revealed that tumor size, number of nodules and TNM stage were independent risk factors associated with successful ablation in patients with DTC with CLNM who received 2 doses of I-131 therapy. I-131 administration is a useful therapy to eradicate cervical lymph node metastasis in patients with DTC, and may be preferentially indicated in patients with DTC with CLNM who are aged <45 years, with tumor sizes <2 cm, solitary nodules and lower TNM stages, in order to control and prevent recurrence and/or metastases.