Abstract: Background and purpose: Radioactive iodine-refractory differentiated thyroid cancer (RAIR-DTC) is a big challenge in the treatment of thyroid cancer. This study aimed to evaluate the therapeutic effect of apatinib mesylate in the treatment of RAIRDTC cervical lymph node metastasis combined with thyroglobulin (Tg), a serum marker of thyroid cancer. Methods: Nine patients who were diagnosed as having progressive RAIR-DTC were enrolled in this study from Jan. 2016 to Dec. 2017. Patients received oral apatinib 750 mg once a day. Patients continued to be treated until the disease progressed or they were unable to tolerate adverse events. Cervical ultrasound were performed, and serum Tg levels were measured regularly after apatinib treatment to evaluate the response. Results: Of the 9 patients in this study, 5 were males and 4 were females with an average age of 52.6 (33-65) years. The baseline average maximum diameter of the largest metastatic cervical lymph nodes was 29.1 mm, and the average maximum diameter was 20.0 mm after 8 to 12 weeks of apatinib treatment. A mean decline of 31.3% could be observed. Of the 8 patients with evaluable Tg, all (100%) patients had a decrease in Tg levels after treatment with apatinib, which was 96.3% lower than the baseline. Conclusion: Ultrasound detection of metastatic cervical lymph node combined with serum Tg level, confirms that apatinib can be used for the treatment of RAIR-DTC.

Key words: Apatinib, Radioactive iodine-refractory differentiated thyroid cancer, Ultrasound, Thyroglobulin