Intraoperative Fractions of Inspiratory Oxygen Are Associated With Recurrence-Free Survival After Elective Cancer Surgery.

Choice of the fraction of inspiratory oxygen (FiO) is controversial. The objective of this analysis was to evaluate whether intraoperative FiO was associated with recurrence-free survival after elective cancer surgery. In this single-center, retrospective study, we analyzed 1,084 patients undergoing elective resection of pancreatic ( = 652), colorectal ( = 405), or hepatic cancer ( = 27) at Heidelberg University Hospital between 2009 and 2016. Intraoperative mean FiO values were calculated. For unstratified analyses, the study cohort was equally divided into a low- and a high-FiO group. For cancer-stratified analyses, this division was done within cancer-strata. The primary outcome measure was recurrence-free survival until the last known follow-up. Groups were compared using Kaplan-Meier analysis. A stratified log rank test was used to control for different FiO levels and survival times between the cancer strata. Cox-regression analyses were used to control for covariates. Sepsis, reoperations, surgical-site infections, and cardiovascular events during hospital stay and overall survival were secondary outcomes. Median FiO was 40.9% (Q1-Q3, 38.3-42.9) in the low vs. 50.4% (Q1-Q3, 47.4-54.7) in the high-FiO group. Median follow-up was 3.28 (Q1-Q3, 1.68-4.97) years. Recurrence-free survival was considerable higher in the high-FiO group ( < 0.001). This effect was also confirmed when stratified for the different tumor entities ( = 0.007). In colorectal cancer surgery, increased FiO was independently associated with increased recurrence-free survival. The hazard for the primary outcome decreased by 3.5% with every 1% increase in FiO. The effect was not seen in pancreatic cancer surgery and we did not find differences in any of the secondary endpoints. Until definite evidence from large-scale trials is available and in the absence of relevant clinical conditions warranting specific FiO values, perioperative care givers should aim for an intraoperative FiO of 50% in abdominal cancer surgery as this might benefit oncological outcomes.