Cancer is the second leading cause of death after cardiovascular disease in Europe and around much of the world. Death from cancer usually results from metastasis, the spread of cancer and its uncontrolled growth in organs other than the primary origin of the tumour, or local recurrence. Surgery to remove the primary tumour is usually a cornerstone of treatment of solid tumours such as breast, lung and colon cancer. However, despite effective macroscopic tumour removal during cancer surgery, there inevitably remain microscopic traces of cancer, or minimal residual cancer and circulating tumour cells. Whether this minimal residual cancer is eliminated by the patient’s immune system or survives to embed in another organ and flourishes to become a future metastasis depends on the balance of conflicting factors in the perioperative period. Evidence from cell culture and live animal inoculation models of cancer has demonstrated that factors tending to inadvertently promote cancer cell survival include surgery and the surgical stress response, some but not all general anaesthetic agents, acute postoperative pain and use of opioid analgesia. Factors tending to resist cancer cell survival are the state of innate immune function, including Natural Killer cells, and perhaps a direct effect of certain anaesthetic and analgesic drugs used perioperatively, including Non-Steroidal Anti-inflammatory Drugs (NSAIDs) and amide local anaesthetics.

The COST Action group developed the hypothesis that anaesthetic, analgesic or other perioperative interventions may influence recurrence or metastasis after primary cancer surgery and has published the majority of available evidence worldwide, both supporting and refuting the hypothesis. Investigators who are pioneers in this field met at a workshop sponsored by the top-ranked journal in the specialty in May 2013, which resulted in a Special Issue of the British Journal of Anaesthesia (BJA) on anaesthesia and cancer, published in July 2014. A consensus statement was published in the same Special Issue which highlighted the relevance of the question and the central role of the proposed COST action group in leading the research agenda. The subject has been nominated at the top of research priority setting exercises for the specialty of anaesthesia, hence underlining the relevance of the subject.

The timeliness of this COST Action is apt because it follows from the BJA’s Special Issue on anaesthesia and cancer and builds momentum to propose both translational research investigating mechanisms by which perioperative interventions might influence postoperative cancer outcome and prospective, randomised trials which will ultimately provide definitive evidence whether particular perioperative interventions during primary cancer surgery have a causal effect on recurrence or metastasis in a particular tumour.