Anaesthetic Type and Survival in Metastatic Colorectal Cancer: A Nationwide Registry Study

The impact of anaesthetic choice on survival following metastatic cancer surgery is uncertain. Inhalational anaesthetics, such as sevoflurane, may promote inflammation and tumour progression, while the intravenous agent propofol has been suggested to be anti-inflammatory. This study aimed to evaluate the association between anaesthetic maintenance with inhalational anaesthesia versus propofol-based total intravenous anaesthesia and overall survival in patients undergoing surgery for metastatic colorectal cancer.

Adult patients (≥ 18 years) with metastatic colorectal cancer who underwent elective or emergency surgery under general anaesthesia from 2014 to 2019 were identified in the Swedish Colorectal Cancer Registry and matched with the Swedish Perioperative Registry. Cox regression, propensity score-matching (2:1, inhalational anaesthesia: propofol), and Kaplan-Meier analysis were used to assess survival.

Of the 1233 included patients, 1011 received maintenance anaesthesia with an inhalational agent, and 222 received propofol. Cox regression analysis identified significant associations between overall survival and advanced age, higher ASA class, emergency surgery, open surgical approach and right-sided tumour location. Comparison of anaesthetics for the full unmatched cohort observed a statistically significant increased risk of death with propofol (hazard ratio [HR] 1.26, 95% CI 1.02-1.55, p = 0.032). Propensity score-matching yielded 639 matched patients (inhalants 426; propofol 213) with Kaplan-Meier analysis showing comparable survival between groups, with 1- and 3-year survival rates of 75% and 43% for inhalants versus 73% and 41% for propofol. In the matched cohort, the HR for propofol versus inhalants in a Cox regression analysis was 1.13 (95% CI 0.89-1.42, p = 0.32).

An apparent association between propofol maintenance and increased mortality observed in the full unmatched cohort was not confirmed in the propensity score-matched cohort. Poorer survival was independently associated with advanced age, higher ASA class, right-sided tumours and open surgical approach.

It is still not known if clinical anaesthetic exposure can affect cancer outcomes. This retrospective analysis of metastatic colorectal cancer surgical cases looked for associations for anaesthesia management factors, or maintenance of anaesthesia with propofol or inhalational agents, and long-term survival. When the anaesthesia exposure cases were matched for other known mortality risk factors, there was no anaesthesia-related mortality risk difference over time between groups in this cohort.