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

In 2016, the World Health Organization (WHO) recommended the use of perioperative hyperoxia (FiO₂ > 0.8) to reduce the risk of postoperative surgical site infections (SSIs). However, the WHO also highlighted potential adverse effects associated with hyperoxia, including increased cancer recurrence and mortality. This study aims to evaluate whether perioperative hyperoxia (FiO₂ > 0.8), compared to conventional oxygen therapy (FiO₂ < 0.4), is associated with increased cancer recurrence and mortality in patients undergoing curative elective colorectal cancer surgery.

This study is a follow-up of a previously published cohort originally designed to assess whether FiO₂ > 0.8 was associated with a higher incidence of perioperative cardiovascular complications. In this follow-up, oncological recurrence and mortality events were recorded at least three years after the index surgery. The primary outcome was recurrence-free survival over the follow-up period, analyzed using Kaplan-Meier curves and a Cox proportional hazards model. The secondary outcome was the 3-year mortality rate, analyzed using the Chi-square test.

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.