Auricular Point Stimulation Plus Dexamethasone for Nausea and Vomiting Caused by Trastuzumab Deruxtecan

Inclusion Criteria: Patients must meet the following inclusion criteria for the study: * Age ≥ 18 years and ≤ 85 years; * Breast cancer patients scheduled to undergo palliative treatment with trastuzumab deruxtecan; * ECOG performance status score of 0-2; * Normal hematological function (platelet count \> 80×10⁹/L; white blood cell count \> 3×10⁹/L; neutrophil count \> 1.5×10⁹/L); * Serum bilirubin ≤ 1.5 times the upper limit of normal (ULN), and transaminase ≤ 5 times the ULN; * No ascites, no gastrointestinal obstruction, normal coagulation function, and serum albumin ≥ 30g/L; * Child-Pugh classification of liver function is Grade A; * Serum creatinine \< ULN, or calculated creatinine clearance rate \> 50ml/min. Exclusion Criteria: Patients who meet any of the following criteria will be excluded from the study: * Local inflammation or infection of the auricle; * Bleeding tendency or coagulation disorders; * Severe ascites; * Gastrointestinal obstruction; * Hypertensive crisis or hypertensive encephalopathy; * Severe uncontrolled systemic complications such as infection or diabetes mellitus; * Clinically severe cardiovascular diseases, including cerebrovascular accident (within 6 months before enrollment), myocardial infarction (within 6 months before enrollment), hypertension that is not well-controlled despite appropriate medication, unstable angina pectoris, congestive heart failure (NYHA Class 2-4), and cardiac arrhythmias requiring drug treatment; * A history of or physical examination findings indicating central nervous system diseases (e.g., primary brain tumor, epilepsy uncontrolled by standard treatment, any history of brain metastasis or stroke); * Hypersensitivity to any drugs used in the study; * Pregnant or lactating women; * Presence of any other diseases, functional impairment caused by metastatic lesions, or suspicious disorders identified during physical examination, which suggest contraindications to the study drugs or place the patient at high risk of treatment-related complications; * Inability or unwillingness to comply with the study protocol.