Impact of Perioperative Hyperoxia on Cancer Recurrence and Mortality After Elective Colorectal Cancer Surgery

Inclusion Criteria: * Patients over 18 years old; * Scheduled for major elective colorectal surgery under general anaesthesia with tracheal intubation. Exclusion Criteria: * Non-oncologic surgery or non-curative oncological surgery * Pregnant or breastfeeding women * Chronic obstructive pulmonary disease (forced expiratory volume in one second \<50% or in need of domiciliary oxygen thera-py) * Acute coronary event or stroke during the previous six weeks (before the surgery) * Chronic renal failure requiring renal replacement therapy; * Predicted length of stay of less than one day; * Any patient that has received general anaesthesia during the previous month.