Anesthetic technique and cancer recurrence in oncologic surgery: unraveling the puzzle

Surgery/anesthetic technique-stimulated immunosuppression in the perioperative period might cause an increase in cancer-related mortality. Whether anesthetic technique can affect the outcomes of cancer patients remains inconclusive. This review discusses data from the available literature on anesthetic techniques applied in oncologic surgery, the long-term outcomes of anesthetic technique, and their relation to survival and cancer recurrence. Searches of the PubMed database up to June 30, 2016, were conducted to identify publications with the terms "anesthetic technique and cancer recurrence," "regional anesthesia and cancer recurrence," "local anesthesia and cancer recurrence," "anesthetic technique and immunosuppression," and "anesthetic technique and oncologic surgery." Surgery/anesthesia-stimulated activation of the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system (SNS) provides immunosuppression through several soluble factors. Volatile anesthetics and opioids suppress cell-mediated immunity (CMI) and promote the proliferation of cancer cells and angiogenesis, whereas propofol does not suppress CMI and inhibits tumor angiogenesis. Regional anesthesia (RA) protects CMI and diminishes the surgical neuroendocrine stress response by blocking afferent neural transmission that stimulates the HPA axis and SNS, decreasing the requirement for opioids and volatile anesthetics and thereby decreasing cancer recurrence. Preclinical and retrospective studies highlight a potential benefit of anesthetic technique in reducing cancer-related mortality and recurrence by attenuating immunosuppression following surgical treatment in patients with specific types of cancer. Several well-planned, prospective, randomized controlled trials (RCTs) are underway that may provide more conclusive and definitive results regarding the benefits of anesthetic technique on survival in oncologic surgery.