This study evaluates if the activity of one-day of NEPA plus dexamethasone, to prevent chemotherapy-induced nausea and vomiting in breast cancer patients receiving adjuvant AC-based chemotherapy, is maintained during all the chemotherapy cycle treatment (maximum 4 cycles).

Patients included in the study should be treated with the following antiemetic prophylaxis, during all the AC-based chemotherapy cycles, up to a maximum of 4 cycles:

• NEPA will be administered orally at the dose of 300 mg netupitant/0.5 palonosetron 1 hour before the start of any chemotherapy cycle.
• Dexamethasone 12 mg will be added on day 1 only of each cycle.

Inclusion Criteria:

1. Women ≥ 18 years old
2. Histologically or cytologically confirmed diagnosis of breast cancer
3. Naïve patients
4. Be scheduled to receive adjuvant chemotherapy with anthracycline (doxorubicin or epirubicin) + cyclophosphamide (AC-based regimen)
5. ECOG (Eastern Cooperative Oncology Group) performance status 0-2
6. Body Mass index (BMI) ≥ 18.5
7. Written informed consent
8. If women of childbearing potential age: reliable contraceptive measures must be used during the study treatment period and up to 30 days after last NEPA administration
9. Acceptable hepatic function (<= 2 times the upper limit of normal for liver transaminases) and renal function (creatinine < 1.5 times the upper limit of normal);
10. Ability and willingness of the patient to complete the diary.

Exclusion Criteria:

1. Advanced/metastatic breast cancer
2. Patients already submitted to non-AC-based chemotherapy
3. Treatment with investigational medications in 30 days before NEPA
4. Myocardial infarction within the last 6 months
5. Documented or known hypersensitivity to 5HT3RA (5-Hydroxytryptamine Receptor 3 Antagonists) or NK1RA (Neurokinin-1 Receptor Antagonists) and excipients
6. Uncontrolled diabetes mellitus
7. Nausea and vomiting at baseline
8. Chronic use of other antiemetic agent(s)
9. Patient's inability to take oral medication
10. Gastrointestinal obstruction or active peptic ulcer
11. Pregnancy or breastfeeding
12. Prior malignancies at other sites except surgically treated non-melanoma skin cancer, superficial cervical cancer, or other cancer from which the patient had been disease-free for ≥ 5 years
13. Psychiatric or CNS (Central Nervous System) disorders interfering with ability to comply with study protocol