Could the perioperative use of opioids influence cancer outcomes after surgery? A scoping review protocol

Background During and after general anaesthesia, opioids are commonly used for pain treatment. Since preclinical studies underlined the potential immunosuppressive activity of these drugs, it was postulated that their perioperative administration could influence cancer outcomes after surgery. Nevertheless, clinical data have been extrapolated mainly from retrospective analyses. Consequently, the precise link between perioperative opioid use and cancer recurrence/metastasis or cancer-related mortality/morbidity is still an unsolved issue. Methods and analysis This scoping review is planned to follow the Joanna Briggs Institute recommendations. The authors will conduct a literature review through the PRISMA statement using PubMed and EMBASE databases; the Grey literature will be explored using Google Scholar and Conference Proceedings Citation Index (via Web of Science). The search strategy will be limited to articles published in the English language and to human studies. The database searches are planned from the inception to January 2022. Two reviewers will independently screen titles and abstracts, followed by a full-text screening of potentially relevant articles with standardised data extraction. Any disagreement for the inclusion between the two reviewers will be discussed with a third reviewer. Ethics and dissemination The review aims to map the available literature, focusing on a possible association between perioperative opioid use and cancer outcomes in patients undergoing surgery. The proposed approach will be useful to identify and analyse the knowledge gap in the field and serve as a prerequisite for future research.