The vast majority of patients treated prophylactically with "first-line" antiemetics in the 5-hydroxytryptamine (5-HT3) receptor antagonist class still have significant PONV. Combination therapies with different pharmacologic bases have the potential to reduce the incidence of PONV. This study is a multicenter, three-arm, prospective study to evaluate the efficacy and safety of aprepitant and ondansetron, monotherapy or in combination, in the prevention of nausea and vomiting after surgery for thyroid cancer.

Postoperative nausea and vomiting (PONV) is the most common complication after surgery, especially thyroidectomy, and the incidence of PONV can be as high as 80% without the administration of prophylactic antiemetics. Currently, available prophylactic interventions for PONV, especially monotherapy, lack universal efficacy. Combination therapy with a different pharmacologic basis has the potential to reduce the incidence of PONV. Previous studies using various 5-HT3 receptor antagonists in combination with aprepitant have shown promising results in reducing the incidence of PONV. The present study is a multicenter, three-arm, prospective study designed to evaluate the efficacy and safety of aprepitant and ondansetron, alone or in combination, in the prevention of postoperative nausea and vomiting in thyroid cancer.

Inclusion Criteria:

1. Patients aged 18-80 years;
2. Voluntary enrollment in the study and signing the informed consent form;
3. Diagnosed with thyroid cancer and needing surgical treatment;

Exclusion Criteria:

1. Patient has depression, history of chronic pain, insulin-dependent diabetes mellitus I or II, history of severe vomiting;
2. history of prior thyroid or neck surgery;
3. Cases in which surgery requiring sternotomy is anticipated;
4. History of long-term hormone use, period of immunosuppressive therapy;
5. pre-operative voice changes or laryngoscopic confirmation of vocal cord paralysis;
6. Pregnant or breastfeeding patients;
7. Patients who are allergic to any of the study medications;
8. Patients who have received any sedative, hypnotic, anxiolytic, opioid, steroid or other antiemetic medication within 24 hours prior to the procedure;
9. Patients taking or planning to take a combination of drugs such as rifampicin, carbamazepine, phenytoin or other drugs that strongly induce CYP3A4 activity;
10. patients with other malignant tumors;
11. Patients with hypothyroidism;
12. Participating or planning to participate in other clinical studies.