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Anesthesia and Long-Term Oncological Outcomes: A Systematic Review and Meta-analysis.

BACKGROUND
Whether propofol elicits a survival benefit over volatile anesthetics during cancer surgery remains inconclusive. The primary aim of this systematic review and meta-analysis is to compare the effects of propofol-based total intravenous anesthesia (TIVA) with any volatile anesthesia on long-term oncological outcomes. The secondary aim is to compare propofol-based TIVA with specific volatile agents on long-term oncological outcomes.


METHODS
We searched PubMed, Embase, Scopus, Web of Science, and Cochrane Library from inception through March 3, 2020. Randomized control trials and observational studies that compared the effects of propofol-based TIVA and volatile anesthesia on long-term oncological outcomes, which also reported hazard ratios (HR) as effect estimates, were considered eligible for inclusion. Using the inverse variance method with a random-effects model, HR and 95% confidence intervals (CI) were calculated. Trial sequential analysis was incorporated to test if the results were subject to a type I or type II error.


RESULTS
Nineteen retrospective observational studies were included. Patients who received propofol-based TIVA during cancer surgery were associated with significantly better overall survival than those who received volatile anesthesia (HR = 0.79, 95% CI, 0.66-0.94, P = .008, I = 82%). In contrast, no statistically significant difference was observed in recurrence-free survival between patients who received propofol-based TIVA and volatile anesthesia during cancer surgery (HR = 0.81, 95% CI, 0.61-1.07, P = .137, I = 85%). In the subgroup analysis by different volatile anesthetics, patients who received propofol-based TIVA were associated with better overall survival than those who received desflurane (HR = 0.54, 95% CI, 0.36-0.80, P = .003, I = 80%). In contrast, there was no statistically significant difference in overall survival between patients who received propofol-based TIVA and those who received sevoflurane (HR = 0.92, 95% CI, 0.74-1.14, P = .439, I = 70%). In the trial sequential analysis of overall survival, the cumulative Z curve reached the required heterogeneity-adjusted information size and crossed the traditional significance boundary. In contrast, in the trial sequential analysis of recurrence-free survival, the cumulative Z curve did not cross the traditional significance boundary. However, the required heterogeneity-adjusted information size has not yet been reached.


CONCLUSIONS
Propofol-based TIVA is generally associated with better overall survival than volatile anesthesia during cancer surgery. Further large-scaled, high-quality randomized control trials are warranted to confirm our findings.