Nitrous Oxide Does Not Increase the Risk of Cancer Recurrence After Colorectal Surgery: A Randomized, Blinded Study
We conducted a 4- to 8-year follow-up of 204 patients with colorectal cancer who were
randomly assigned to 65% nitrous oxide (n=97) or nitrogen (n=107), balanced with isoflurane
and remifentanil. The primary outcome was the time to cancer recurrence. Our primary
analysis was a multivariable Cox-proportional-hazards regression model that included
relevant baseline variables. In addition to treatment group, the model considered patient
age, tumor grade, dissemination, adjacent organ invasion, vessel invasion, and the number of
nodes involved. The study had 80% power to detect a 56% or greater reduction in recurrence
rates (i.e., hazard ratio of 0.44 or less) at the 0.05 significance level.
Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Investigator), Primary Purpose: Prevention
To determine if the risk of colorectal cancer recurrence was similar in patients who were randomly assigned to 65% nitrous oxide or nitrogen during colorectal surgery.
270 days post surrgery
Edith Fleischmann, M.D.
Medical University of Vienna