Effect of inhalational agents in breast cancer surgery on tumour metastasis: Systematic review and meta-analysis.

Abstract

Background and aims: The primary treatment for breast cancer involves surgically removing the affected breast. Different types of anaesthesia used during surgery may have an impact on cancer recurrence. This meta-analysis was conducted to assess the current level of evidence for the impact of the type of anaesthesia for breast cancer surgery on cancer recurrence.

Methods: Following PROSPERO registration, a comprehensive database search was conducted across PubMed, Cochrane, Embase, Scopus, and Google Scholar, encompassing all available data up to December 2024. Randomised controlled trials (RCTs) and retrospective studies assessing the effect of inhalational anaesthetic agents on cancer recurrence after breast cancer surgeries were included. The Cochrane Collaboration's risk of bias and the Newcastle-Ottawa scale were used for risk of bias assessment in RCTs and retrospective studies, respectively. We inverted the hazard ratio (HR) to (1/HR) for studies that reported inhalational as the control group.

Results: Eight studies were included: four RCTs and four retrospective cohort studies. No association between the anaesthetic agent used and the recurrence of breast cancer was seen in RCTs (risk ratio (RR) =1.07, 95% confidence interval (CI): 0.89, 1.29). Included retrospective cohort studies showed RR = 1.46 (95% CI: 1.32, 1.62), showing an association of recurrence with inhalational agents compared to total intravenous anaesthesia-based or regional anaesthesia with significant bias.

Conclusion: The retrospective studies suggest a possible association between inhalational anaesthesia and breast cancer recurrence. However, these findings should be interpreted with caution due to the inherent limitations of retrospective studies, including a higher risk of bias and variability in control group definitions. This contradicts findings from prospective RCTs. Further research is needed to understand the mechanisms behind this association and to weigh the pros and cons of different anaesthesia techniques.