Quantitative Pharmacology-Based Dose Adjustment Protocol in Postoperative Thyroid Cancer Patients

Inclusion criteria

• 1.Aged 18-65 years (inclusive), any gender; 2.Able to fully understand and voluntarily sign the informed consent form; 3.Patients with histologically or cytologically confirmed advanced/metastatic thyroid cancer who are treatment-naïve and require total or near-total thyroidectomy; 4.ECOG performance status ≤ 2; 5.No obvious contraindications to surgery; 6.Body weight ≥ 50.0 kg for males and ≥ 45.0 kg for females, with a body mass index (BMI) of 19.0-26.0 kg/m² (inclusive of 19.0 and 26.0); 7.Subjects with regular daily routines, capable of maintaining good communication with the investigator and complying with all clinical trial requirements, and willing and able to adhere to the scheduled protocol visits, treatment plan, and laboratory assessments; 8.Patients must have adequate baseline organ function at the screening visit, including local laboratory values meeting the inclusion criteria as specified below.

Exclusion criteria

• 1.Thyroid cancer patients whose thyroidectomy does not meet the criteria for total or near-total resection; 2.Patients with prior treatment for thyroid cancer (including surgery and/or medication); 3.Patients who have undergone major surgery (including radiosurgery) or experienced significant traumatic injury within 2 weeks prior to randomization; 4.History of other malignancies within <3 years prior to the initiation of study treatment; 5.Subjects with a known history of positive human immunodeficiency virus (HIV) testing; 6.Known active infection with hepatitis B virus (HBV) or hepatitis C virus (HCV) (chronic or resolved HBV and HCV infections are permitted); 7.Patients with congenital or acquired immunodeficiency; 8.History of clinically significant drug allergy or atopic allergic diseases (e.g., asthma, urticaria, eczematous dermatitis, etc.), or known hypersensitivity to Euthyrox (levothyroxine sodium) or any of its excipients; 9.Pregnant or lactating females.