Clinical Study on the Effect of Selenium Yeast Capsule on Prognosis of Differentiated Thyroid Carcinoma

Inclusion Criteria: 1. Participants have signed informed consent forms； 2. Patients with differentiated thyroid carcinoma diagnosed pathologically after thyroid surgery； 3. Male or female patients aged 18-75 years; 4. Women who are likely to become pregnant must use the appropriate contraceptive method to avoid pregnancy and minimize the likelihood of conception between the beginning of the drug intervention study and the 28th day after the study. Exclusion Criteria: 1. A patient who is pregnant or breastfeeding; 2. Currently, hepatase cytochrome P450 3A4 induction or inhibitor therapy, antiviral therapy for immunodeficiency diseases (note: hepatase induction or inhibitor: phenobarbital phenobarbital sodium rifampicin carbamazepine grisoflomycin and dexamethasone and chloramphenicol allopurinol ketone conazole isoniazid imittidine phenothiazine); 3. Gastrointestinal surgery that may affect the study of drug absorption; 4. The patient has a history of haemoglobin disease or acute progressive nephropathy or autoimmune skin disease; 5. A history of substance abuse and alcohol abuse within the last 1 year; 6. There are therapeutic contraindications with selenium yeast capsules as listed in the instructions; 7. New York Heart Association (NYHA) class III or IV congestive heart failure and/or left ventricular ejection fraction of 40% with a significant cardiovascular history in the past 6 months: myocardial infarction coronary angioplasty or bypass surgery valvular disease or repair of unstable angina transient ischemic attack or cerebrovascular accident; 8. There are obvious abnormalities in liver function; 9. The patient has significant liver disease acute active hepatitis or chronic active hepatitis clinical signs or symptoms； 10. Laboratory and physical examination or ECG findings of any clinically significant abnormality would, in the investigator's judgment, compromise the patient's safety or prevent successful participation in the clinical study； 11. Patients with severe renal insufficiency.