Inclusion Criteria:  Eastern Cooperative Oncology Group (ECOG) status 0 to 2 patient with breast cancer planned to receive Anthracycline and Cyclophosphamide chemotherapy informed consent compliance expected social security affiliation  Exclusion Criteria:  nausea or vomiting 24h or less, before inclusion Antiemetic drug intake in the last 72h before inclusion Central nervous system metastasis Daily alcohol intake Prior chemotherapy Cardiac arrythmia, severe heart failure Device for sleep apnea History of arterial or venous thrombosis, or thrombophlebitis Vagotomy Vagal stimulation ongoing Skin disease on the stimulation zone Cochlear implant next to the stimulation zone Unable to use the vagal stimulation device due to left ear unusual shape Pregnant or breastfeeding women, or women of childbearing age without effective contraception Documented allergy or contraindication to one of the antiemesis drugs required in the study Protected adults (individuals under guardianship by court order) Unable to read or write