Meyhoff, Christian Sylvest4; Jørgensen, Lars Nannestad6; Wetterslev, Jørn5; Siersma, Volkert Dirk7; Rasmussen, Lars S.6
1 Forskningsenheden for Almen Praksis, Eksterne centre, Københavns Universitet2 Section of General Practice, Department of Public Health, Faculty of Health and Medical Sciences, Københavns Universitet3 Department of Clinical Medicine, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet4 Department of Anaesthesiology, Herlev Hospital, University of Copenhagen, Herlev5 unknown6 Department of Clinical Medicine, Department of Clinical Medicine, Faculty of Health and Medical Sciences, Københavns Universitet7 Forskningsenheden for Almen Praksis, Eksterne centre, Københavns Universitet
BACKGROUND: Administration of supplemental oxygen in the perioperative period is controversial, as it may increase long-term mortality. Our aim was to assess the association between 80% oxygen and occurrence of subsequent cancer in patients undergoing abdominal surgery in a post hoc analysis of the PROXI trial. METHODS: The 1386 patients in the PROXI trial underwent elective or emergency laparotomy between 2006 and 2008 with randomization to either 80% or 30% oxygen during and for 2 h after surgery. We retrieved follow-up status regarding vital status, new cancer diagnoses, and new histological cancer specimens. Data were analysed using the Cox proportional hazards model. RESULTS: Follow-up was complete in 1377 patients (99%) after a median of 3.9 yr. The primary outcome of new cancer diagnosis or new malignant histological specimen occurred in 140 of 678 patients (21%) in the 80% oxygen group vs 150 of 699 patients (21%) assigned to 30% oxygen; hazards ratio 1.06 [95% confidence interval (CI) 0.84, 1.34], P=0.62. Cancer-free survival was significantly shorter in the 80% oxygen group; hazards ratio 1.19 (95% CI 1.01, 1.42), P=0.04, as was the time between surgery and new cancer, median 335 vs 434 days in the 30% oxygen group. In patients with localized disease, non-significant differences in cancer and cancer-free survival were found with hazard ratios of 1.31 and 1.29, respectively. CONCLUSIONS: Although new cancers occurred at similar rate, the cancer-free survival was significantly shorter in the 80% oxygen group, but this did not appear to explain the excess mortality in the 80% oxygen group. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov (NCT01723280).
British Journal of Anaesthesia, 2014, Vol 113, Issue suppl. 1