AUTHOR=Dehne Sarah , Spang Verena , Klotz Rosa , Kummer Laura , Kilian Samuel , Hoffmann Katrin , Schneider Martin A. , Hackert Thilo , Büchler Markus W. , Weigand Markus A. , Larmann Jan 

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

JOURNAL=Frontiers in Medicine

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2021.761786

DOI=10.3389/fmed.2021.761786

ISSN=2296-858X

ABSTRACT=<p><bold>Background:</bold> Choice of the fraction of inspiratory oxygen (FiO<sub>2</sub>) is controversial. The objective of this analysis was to evaluate whether intraoperative FiO<sub>2</sub> was associated with recurrence-free survival after elective cancer surgery.</p><p><bold>Methods and Analysis:</bold> In this single-center, retrospective study, we analyzed 1,084 patients undergoing elective resection of pancreatic (<italic>n</italic> = 652), colorectal (<italic>n</italic> = 405), or hepatic cancer (<italic>n</italic> = 27) at Heidelberg University Hospital between 2009 and 2016. Intraoperative mean FiO<sub>2</sub> values were calculated. For unstratified analyses, the study cohort was equally divided into a low- and a high-FiO<sub>2</sub> 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<sub>2</sub> 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.</p><p><bold>Results:</bold> Median FiO<sub>2</sub> 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<sub>2</sub> group. Median follow-up was 3.28 (Q1–Q3, 1.68–4.97) years. Recurrence-free survival was considerable higher in the high-FiO<sub>2</sub> group (<italic>p</italic> &lt; 0.001). This effect was also confirmed when stratified for the different tumor entities (<italic>p</italic> = 0.007). In colorectal cancer surgery, increased FiO<sub>2</sub> was independently associated with increased recurrence-free survival. The hazard for the primary outcome decreased by 3.5% with every 1% increase in FiO<sub>2</sub>. The effect was not seen in pancreatic cancer surgery and we did not find differences in any of the secondary endpoints.</p><p><bold>Conclusions:</bold> Until definite evidence from large-scale trials is available and in the absence of relevant clinical conditions warranting specific FiO<sub>2</sub> values, perioperative care givers should aim for an intraoperative FiO<sub>2</sub> of 50% in abdominal cancer surgery as this might benefit oncological outcomes.</p>