Mortality among
cancer patients is more commonly due to the effects of
metastasis and recurrence as opposed to the primary tumour. Various perioperative factors have been implicated in tumour growth, including
anesthetic agents and
analgesia techniques. In this narrative review, we integrate this information to present a summary of the best available evidence to guide the conduct of
anesthesia for primary
cancer surgery.
SOURCE: There is conflicting evidence regarding volatile agents; however, the majority of studies are in vitro, suggesting that these agents are associated with enhanced expression of tumourigenic markers as well as both proliferation and migration of
cancer cells.
Nitrous oxide has not been shown to have any effect on
cancer recurrence.
Local anesthetic agents may reduce the incidence of
cancer recurrence through systemic anti-inflammatory action in addition to direct effects on the proliferation and migration of
cancer cells. Nonsteroidal anti-inflammatory drugs affect
cancer cells via inhibition of
cyclooxygenase 2 (COX-2), which leads to reduced resistance of the
cancer cell to apoptosis and reduced production of
prostaglandins by
cancer cells. Nonsteroidal anti-inflammatory drugs also suppress the
cancer cell growth cycle through effects independent of COX-2 inhibition.
Opioids have been shown to inhibit the function of natural killer cells and to stimulate
cancer cell proliferation through effects on angiogenesis and tumour cell signalling pathways. Supplemental
oxygen at the time of surgery has a proangiogenic effect on
micrometastases, while the use of perioperative
dexamethasone does not affect overall rates of
cancer survival.
CONCLUSIONS: Current laboratory research suggests that perioperative interventions may impact recurrence or
metastasis through effects on
cancer cell signalling, the immune response, or modulation of the neuroendocrine stress response. Further evidence is awaited from prospective randomized-controlled trials. Meanwhile, with limited data upon which to make strong recommendations, anesthesiologists should seek optimal
anesthesia and analgesia for their patients based on individual risk-benefit analysis and best available evidence on outcomes other than
cancer recurrence.