The Effect of Anesthetic Technique on Survival in Human Cancers: A Meta-Analysis of Retrospective and Prospective Studies

Animal models have shown that regional anesthesia (combined with or without general anesthesia) would attenuate the surgical stress response by preserving immune function and result in better long-term outcome. In order to test the hypothesis that cancer patients who had surgery with epidural anesthesia (EA) would have better outcome (either overall survival [OS] or recurrence-free survival [RFS]) than those who were general anesthesia (GA), we performed this meta-analysis. By searching relevant literature, a total of 14 studies containing 18 sub-studies (seven in OS analysis and eleven in RFS analysis) were identified and meta-analyzed. Adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) were used to assess the strength of association. For OS, the random-effects model was used to analyze the data and demonstrated an OS benefit in favor of EA compared with GA alone (HR = 0.84, 95% CI 0.74-0.96, P = 0.013). The influence analysis showed the robustness of the results. Specifically, a significantly positive association between EA and improved OS was observed in colorectal cancer (HR = 0.65, 95% CI 0.43-0.99, P = 0.045). For RFS, the random-effects model was used to analyze the data and no significant relationship between RFS benefit and EA (HR = 0.88, 95% CI 0.64-1.22, P = 0.457) was detected. In conclusion, our meta-analysis suggests that epidural anesthesia and/or analgesia might be associated with improved overall survival in patients with operable cancer undergoing surgery (especially in colorectal cancer), but it does not support an association between epidural anesthesia and cancer control. Prospective studies are needed to determine whether the association between epidural use and survival is causative.