An In Vivo Mouse Model of Total Intravenous Anesthesia during Cancer Resection Surgery.

Anesthesia is a routine component of cancer care that is used for diagnostic and therapeutic procedures. The anesthetic technique has recently been implicated in impacting long-term cancer outcomes, possibly through modulation of adrenergic-inflammatory responses that impact cancer cell behavior and immune cell function. Emerging evidence suggests that propofol-based total intravenous anesthesia (TIVA) may be beneficial for long-term cancer outcomes when compared to inhaled volatile anesthesia. However, the available clinical findings are inconsistent. Preclinical studies that identify the underlying mechanisms involved are critically needed to guide the design of clinical studies that will expedite insight. Most preclinical models of anesthesia have been extrapolated from the use of anesthesia in in vivo research and are not optimally designed to study the impact of anesthesia itself as the primary endpoint. This paper describes a method for delivering propofol-TIVA anesthesia in a mouse model of breast cancer resection that replicates key aspects of clinical delivery in cancer patients. The model can be used to study mechanisms of action of anesthesia on cancer outcomes in diverse cancer types and can be extrapolated to other non-cancer areas of preclinical anesthesia research.

Implicating anaesthesia and the perioperative period in cancer recurrence and metastasis.

Cancer, currently the leading cause of death in the population aged less than 85 years, poses a significant global disease burden and is anticipated to continue to increase in incidence in both developed and developing nations. A substantial proportion of cancers are amenable to surgery, with more than 60% of patients undergoing tumour resection. Up to 80% of patients will receive anaesthesia for diagnostic, therapeutic or palliative intervention. Alarmingly, retrospective studies have implicated surgical stress in disease progression that is predominantly characterised by metastatic disease-the primary cause of cancer-associated mortality. Our understanding of the mechanisms of surgical stress and impact of perioperative interventions is, however, far from complete. Accumulating evidence from preclinical studies suggests that adrenergic-inflammatory pathways may contribute to cancer progression. Importantly, these pathways are amenable to modulation by adapting surgical (e.g. minimally invasive surgery) and anaesthetic technique (e.g. general vs. neuraxial anaesthesia). Disturbingly, drugs used for general anaesthesia (e.g. inhalational vs. intravenous anaesthesia and potentially opioid analgesia) may also affect behaviour of tumour cells and immune cells, suggesting that choice of anaesthetic agent may also be linked to adverse long-term cancer outcomes. Critically, current clinical practice guidelines on the use of anaesthetic techniques, anaesthetic agents and perioperative adjuvants (e.g. anti-inflammatory drugs) during cancer surgery do not take into account their potential effect on cancer outcomes due to a lack of robust prospective data. To help address this gap, we provide an up-to-date review of current clinical evidence supporting or refuting the role of perioperative stress, anaesthetic techniques and anaesthetic agents in cancer progression and review pre-clinical studies that provide insights into biological mechanisms.