The role of regional anaesthesia in the emerging subspecialty of onco-anaesthesia: a state-of-the-art review.

Cancer accounts for millions of deaths globally each year, predominantly due to recurrence and metastatic disease. The majority of patients with primary solid organ cancers require surgery, however, some degree of tumour dissemination related to surgery is inevitable. The surgical stress response and associated immunosuppression, pain, inflammation, tissue hypoxia and angiogenesis have all been implicated in promoting tumour survival, proliferation and recurrence. Regional anaesthesia was hypothesised to reduce the surgical stress response and immunosuppression, minimise the need for volatile anaesthesia and reduce pain and opioid requirements, thus mitigating pro-tumour pathways associated with the peri-operative period and improving long-term oncological outcomes. While some retrospective studies suggested an association between regional anaesthesia and reduced cancer recurrence, the first large randomised controlled trial on the effect of anaesthetic technique on cancer outcome found no significant difference between paravertebral regional anaesthesia and volatile anaesthesia with opioid analgesia in patients undergoing breast cancer surgery. Randomised controlled trials on the long-term oncological outcomes of regional anaesthesia in other tumour types are ongoing. The focus on how peri-operative interventions, especially regional anaesthesia, during cancer resection surgery, may enhance short-term recovery and perhaps influence long-term outcome has spawned the global emergence of the subspecialty of onco-anaesthesia. This review aims to discuss the most recent evidence on the use of regional anaesthesia in cancer surgery and the significance of its role in onco-anaesthesia.