Immunological Insights into Opioid-Free Anaesthesia in Oncological Surgery: A Scoping Review

PURPOSE OF REVIEW: The influence of opioids on outcomes after cancer surgery when used, or avoided, intraoperatively remains unclear. There is a need to conduct a scoping review to explore the wider context and provide direction for future research. The review will examine the current state of evidence in humans, with a focus on immunological biomarkers and clinically relevant cancer outcomes in trials comparing opioid-free to opioid-based general anaesthesia. RECENT FINDINGS: There is limited research on this subject area, which is mainly focused on breast cancer. The most frequently evaluated immunological parameter is the neutrophil-to-lymphocyte ratio. Cancer outcomes are mainly focused on recurrence. SUMMARY: The central knowledge gap is understanding how the cellular effects of opioids translate into longer-term patient outcomes. The major challenge for future research is accounting for the immunomodulatory effects of a wide range of confounding factors, which have yet to be clarified. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11912-022-01300-5.