To Örebro University

Background:Clinical studies in humans as well as experimental evidence from animal studiessuggests that the immune system plays an important role in perioperative metastases following cancer surgery. However, the precise role of the different components of the immune system in this process appears conflicting. Our primary aim was to assess T cell activity and natural killer (NK) cell toxicity in patients undergoing prostate cancer surgery and randomized to epidural or intravenous analgesia.

Methods:26 patients were randomized to receive general anaesthesia and patient controlled analgesia (PCA) with morphine postoperatively (Group P) or combined, general and epidural anaestesia with patient-controlled thoracic epidural analgesia postoperatively (Group E). Blood sample were obtained perioperatively at different time points for analyses of: subpopulations of leukocytes, cell- ediated immune response after mitogen stimulation, NK cell cytotoxicity, vascular endothelial growth factor (VEGF), IFN-g/IL-10 ratio, C-reactive protein (CRP) and white blood cell (WBC) count. In addition, pain and morphine consumtion were also determined.

Results: T lymphocytes decreased more in Group P compared to Group E at 24 hours postoperatively while T-helper lymphocytes decreased more in Group E compared to Group P at the same time point without reaching statistically significant difference.No differences were seen in NK cells or cytotoxic T lymphocytes between the groups. The CD4+/CD8+ ratio remained constant between the groups over time. Natural Killer Cell cytotoxicity did not show statistically significant differences between the groups at the different postoperative time points. No other differences ere found between the groups except in pain intensity which was lower in Group E, and morphine consumption which was greater in Group P. Conclusions:Our findings suggest that regional anaesthesia and analgesia appears to play a minor role in immunomodulation following surgery for prostate cancer. If regional anesthesia does prevent tumour growth or metastases perioperatively, the mechanism for this needs to be further elucidated.