Inclusion Criteria:  Patients ≥ 18 year old. Scheduled surgery for breast cancer liver metastases between January 1st 2010 and December 31st 2015 American Society of Anesthesiologists (ASA) score I-III. They have signed the informed consent.  Exclusion Criteria:  Patients under 18 year old. ASA ≥ IV. Urgent surgery. Patients who have not signed the informed consent.