Effects of general anesthesia with or without epidural block on tumor metastasis and mechanisms

The present study aimed to assess whether different anesthesia methods (general anesthesia and general anesthesia combined with epidural block) were associated with tumor metastasis during the perioperative period and the possible molecular mechanisms of tumor metastasis. A rat hepatoma tumor xenograft model was constructed via the subcutaneous injection of Morris hepatoma 3924A cells into the upper axillary fossa. General anesthesia and general anesthesia combined with epidural block prior to hepatectomy were conducted on tumor-bearing rats. The average numbers of metastatic nodules on the lung surface were calculated in the different groups and the presence of abdominal lymph node metastases, rate of malignant ascites and abdominal wall-implanted nodules were recorded. Blood samples were collected from the orbits of rats immediately prior to surgery and at 2, 7 and 30 days following surgery. Plasma levels of interferon-γ, transforming growth factor-α and vascular endothelial growth factor (VEGF) were measured. Finally, the expression of phosphorylated signal transducer and activator of transcription-3 and phosphorylated VEGF were measured by western blot analysis. The results of this analysis demonstrated that tumor metastasis was greatly suppressed when the rats underwent general anesthesia combined with epidural block prior to hepatectomy, compared with general anesthesia alone. The results of cytokine quantification and western blot analysis revealed that the anti-metastatic effect of general anesthesia combined with epidural block may have been mediated by inhibition of STAT3 and the relevant cytokines.