Anesthetic and Analgesic Influence on Cancer Recurrence and Metastasis.

Cancer is one of the leading causes of death in the United States. Total resection of tumors can be curative; however, investigators have speculated that inflammatory, metabolic, neuroendocrine, and immunologic changes that occur perioperatively may be promoted or induced by anesthetics. The influence of anesthetic choice on cancer recurrence and metastasis has yet to be definitively linked. Retrospective, animal model, and in vitro studies investigating volatile anesthetics, local anesthetics, and intravenous analgesics have resulted in contradicting findings. Results ranged from no association between type of anesthetic used and cancer recurrence, to immune-protective effects inhibiting tumor cell growth, or immune-suppressive effects promoting tumor cell growth or metastasis. It has yet to be confirmed whether volatile anesthetics, intravenous anesthetics, and analgesics are causal factors for cancer metastasis or recurrence. There are increasing data suggesting the immunosuppressant effects of anesthesia can be circumvented by avoiding opioids and volatile anesthetics. Further evaluation is required to determine the implications of regional anesthesia and propofolbased total intravenous anesthesia on cancer recurrence. Several ongoing randomized controlled trials are studying this link. Changes to clinical practice cannot definitively be recommended until the results of these studies can be examined.