Study of Neoadjuvant Regimen for Radioactive Iodine Treatment of Metastatic and Advanced Differentiated Thyroid Cancers

Inclusion Criteria:

1. The patient volunteers and signs an informed consent form.
2. age ≥18 and \<99 years old;
3. Diagnosed as differentiated thyroid cancer (DTC) by histopathology;
4. surgically inoperable and/or recurrent/metastatic differentiated thyroid cancers;
5. Did not receive molecular targeting treatment; Prior RAI therapy is allowed if \> 3 months prior to initiation of therapy on this protocol and evidence of progression (as defined above) has been documented in the interim.
6. There must be at least one measurable lesion (according to RECIST v1.1);
7. Physical condition ECOG PS: 0-2;
8. Expected survival time ≥ 3 months;
9. Laboratory tests meet the following criteria: Bone marrow function: absolute count of blood neutrophils (ANC) ≥1.5×109/L; platelet (PLT)≥100×109/L; hemoglobin (HB)≥90g/L; Liver function: alanine aminotransferase (ALT), aspartate aminotransferase (AST) ≤ULN\*2.5
10. Well controlled blood pressure prior to study entry.
11. At least one or more hypermetabolic lesions other than the neck on 18F-FDG PET scans

Exclusion Criteria:

1. Anaplastic thyroid carcinoma, thyroid lymphoma, mesenchymal tumors of the thyroid, metastases to the thyroid;
2. Previous treatment with chemotherapy for anti-thyroid cancer (allowing low-dose chemotherapy for radiation sensitization) or treatment with thalidomide or its derivatives;
3. Previous treatment with VEGFR-TKI small molecule drugs within 1 month, such as vandetanib, cabozantinib, lenvatinib, sunitinib, sorafenib, etc.;
4. Major surgery within 4 weeks prior to enrollment, or received anti-thyroid cancer radiotherapy;
5. Severe cardiovascular disease, including hypertension (BP≥140/90mmHg) uncontrolled by medical treatment, unstable angina, history of myocardial infarction, congestive heart failure\>NYHA II, Marked baseline prolongation of QT/corrected QT (QTc) interval;
6. Severe infection requires intravenous antibiotic, antifungal or antiviral treatment;
7. Active hemoptysis (bright red blood of at least one-half teaspoon) in the 28 days prior to study entry;
8. Suffering from mental illness, poor compliance;
9. Pregnant women will be ineligible; breast feeding should be discontinued if the mother is treated with Apatinib;
10. Embolization and bleeding occurred within 4 weeks before enrollment;
11. Patient with a risk of gastrointestinal bleeding; abnormal coagulation function (INR \> 1.5, APTT \> 1.5 × ULN);
12. Arteriovenous thrombosis such as cerebrovascular accidents, deep vein thrombosis, and pulmonary embolism within 12 months prior to screening;
13. A variety of factors that affect the absorption of oral medications (such as inability to swallow, nausea and vomiting, chronic diarrhea and intestinal obstruction)