Impact of anesthesia for cancer surgery: Continuing Professional Development

A number of original publications and review articles have addressed the issue of perioperative immune modulation and cancer outcome. The objective of this module is to review current understanding surrounding the pathways involved and the evidence implicating commonly used anesthetic agents. Drugs commonly used in anesthetic practice have been shown to affect various components of the immune system in laboratory animal and human in vitro models. It has been hypothesized that these effects may favour tumour recurrence and metastasis formation. Inhalational agents and opiates have potential negative immunomodulatory effects; on the other hand, regional anesthesia and propofol may have positive effects on immune function modulation. However, the clinical relevance of these studies to human cancer outcome is unknown since clinical trials are equivocal, and results of in vitro and animal model studies cannot be extrapolated to clinical practice. Furthermore, there is a lack of rigorous clinical trials demonstrating clinical outcome benefit for one technique over another. It remains unclear how anesthetic drugs influence the immune system in relation to tumour cell elimination and clinical cancer outcome. Recommendations for a specific anesthetic technique based on cancer outcome alone cannot be made. A pragmatic solution would be to offer regional anesthesia in isolation or combined with propofol infusion to cancer patients if appropriate and if local expertise is available. Regional anesthesia offers excellent analgesia, a low incidence of postoperative nausea and vomiting, and a favourable immunological profile based on current understanding of laboratory evidence.