Abstract: Objective The Objective of our study was to investigate the short-term efficacy and safety of ¹³¹I combined with apatinib in the treatment of lung metastasis from differentiated thyroid cancer.Methods A retrospective analysis of 57 patients with lung metastases from differentiated thyroid cancer who were treated in our department from October 2018 to October 2020 were divided into the control group(n=30)and the combined treatment group(n=27).The control group was treated with ¹³¹I alone,and the combination group was treated with ¹³¹I combined with apatinib.In both groups of patients,the levels of thyroglobulin(Tg)and baseline diameter were observed and recorded every six months.The changes of baseline diameter changes of target lesions(TL)and concentration range count/background count(C/B)were observed and recorded every six months.At the same time,the adverse reactions of patients in the two groups were recorded.Results After the follow-up,the level of Tg in the combined treatment group(36.34±19.72 μg/L)was significantly lower than that in the control group(122.18±22.98 μg/L),and the difference was statistically significant(P＜0.001).The mean diameter of TL in the combined treatment group(3.55±0.39 mm)was significantly smaller than that of the control group(14.01±1.44 mm),and the difference was statistically significant(P＜0.001).After 24 months,DCR and ORR in the combined treatment group were higher than those in the control group(P＜0.01).The C/B value of the combined treatment group(2.98±0.54)was significantly lower than that of the control group(25.45±3.00),and the difference was statistically significant(P＜0.001).The common adverse reactions of apatinib in the combined treatment group were hand-foot syndrome(6 cases),hypertension(4 cases),and rash(2 cases).No serious adverse reactions of grade Ⅲ or above related to apatinib were observed.Conclusion ¹³¹I combined with apatinib is effective in the treatment of lung metastasis from differentiated thyroid cancer,has obvious tumor shrinkage effect and achieves a high biochemical remission rate,while the side effects are mild and controllable,and the safety is high.

Key words: ¹³¹I, Apatinib, Differentiated thyroid cancer, Lung metastasis, Thyroglobulin