The goal of this clinical trial is to learn if auricular point stimulation plus dexamethasone works to effectively prevent or suppress nausea and vomiting caused by docetaxel combined with cyclophosphamide in breast cancer adjuvant chemotherapy. It will also learn about the safety and influence on gastrointestinal function of auricular point stimulation plus dexamethasone.

The main questions it aims to answer are:

Can auricular point stimulation plus dexamethasone effectively prevent or suppress nausea and vomiting induced by the docetaxel plus cyclophosphamide regimen? Can auricular point stimulation plus dexamethasone effectively reduce the incidence of appetite loss, weakened or disordered gastrointestinal function, and other uncomfortable conditions caused by excessive use of antiemetic drugs?

Participants will:

Receive auricular acupressure with bean seeds on specific points of one ear, plus intravenous injection of dexamethasone as a preventive antiemetic treatment within half an hour before chemotherapy. Starting from the day of chemotherapy (Day 1) to the following five days (Day 1-Day 5), provide regular stimulation at the acupressure points daily by themselves according to the protocol provided in this trial. Record their nausea and vomiting status, appetite, and gastrointestinal function-related symptomatic indicators from Day 1 to Day 5. Oral antiemetics are also prepared. If nausea and vomiting are significant or the patient feels the need, they may be temporarily administered as an adjunct.

Docetaxel combined with cyclophosphamide is one of the most commonly used chemotherapy regimens for postoperative adjuvant treatment of breast cancer. While it improves patients' survival rate, it is accompanied by certain gastrointestinal adverse reactions, among which chemotherapy-induced nausea and vomiting (CINV) is relatively common, with an incidence rate ranging from 16% to 54%. The vast majority of cases occur on the day of medication and within 4 days thereafter. This regimen is defined as a chemotherapy regimen with low to moderate emetogenic risk in current clinical guidelines. The recommended preventive antiemetic strategy usually consists of glucocorticoids (e.g., dexamethasone) combined with 5-HT3 receptor antagonists (e.g., ondansetron, palonosetron, etc.). It can be strengthened with NK1 receptor antagonists (e.g., fosaprepitant, aprepitant) and the antipsychotic olanzapine, depending on clinical circumstances. However, in clinical practice, many patients experience drug-related gastrointestinal adverse reactions such as anorexia, abdominal distension, constipation, and diarrhea due to receiving high-intensity antiemetic therapy. Studies have shown that the incidence of constipation in chemotherapy patients treated with palonosetron approximately doubles. The high-intensity use of antiemetic drugs seriously impairs patients' gastrointestinal function and quality of life, and even affects their treatment compliance. Therefore, how to effectively prevent CINV while minimizing the side effects caused by antiemetic therapy itself has become a practical issue that medical staff need to pay urgent attention to.

Auricular point pressotherapy is a traditional Chinese medicine (TCM) external therapy. It involves accurately pasting Vaccaria seeds on corresponding auricular points with adhesive tapes and stimulating the points through moderate pressing to regulate physical functions and treat diseases. According to TCM theory, the ear is closely connected to the internal organs and meridians of the human body, and all twelve meridians are directly or indirectly linked to the ear. Auricular point pressotherapy can unblock meridians and balance yin and yang by stimulating corresponding auricular points, thereby alleviating CINV and other adverse reactions. It is an economical, non-invasive, and low-side-effect natural therapy. Meanwhile, auricular point pressotherapy can effectively improve gastrointestinal function, thus significantly reducing gastrointestinal dysfunction caused by chemotherapy and antiemetic drugs, such as anorexia, abdominal distension, constipation, and diarrhea.

Our team summarized the relevant data of patients who voluntarily received auricular point pressotherapy for antiemesis previously. The results showed that among breast cancer patients who received docetaxel combined with cyclophosphamide for postoperative adjuvant chemotherapy, 100% of those treated with auricular point pressotherapy plus dexamethasone did not experience grade 2 or above (including grade 2) nausea and had no vomiting on the day of medication and within 3 days thereafter.

Based on the above theoretical and practical basis, this study intends to evaluate the efficacy and safety of auricular point pressotherapy combined with dexamethasone for CINV induced by docetaxel plus cyclophosphamide in postoperative adjuvant chemotherapy for breast cancer. At the same time, it will assess related indicators such as patients' appetite and gastrointestinal function, and explore the important role of integrated traditional Chinese and Western medicine intervention in improving patients' quality of life during chemotherapy, to provide clinical reference for optimizing the management of adverse reactions of this chemotherapy regimen.

Inclusion Criteria: Patients must meet the following inclusion criteria for the study:

• Age ≥ 18 years and ≤ 85 years
• After a radical mastectomy, further postoperative adjuvant chemotherapy with docetaxel combined with cyclophosphamide regimen is required.
• 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