This Saturday session at Euroanaesthesia 2019 in Vienna discussed one of the most controversial issues in the specialty: the influence of different anaesthetic drugs and techniques on cancer cells, and the likelihood of tumour recurrence.
The speakers discussed evidence that some opioid and hypnotic agents may promote cancer recurrence, that local anaesthetic agents and loco-regional techniques may reduce the likelihood, and that intravenous anaesthesia may also reduce the incidence of recurrence.
The first talk on opiates, regional anaesthesia and cancer recurrence was given by Professor Daniela Ionescu, Head, Department of Anesthesia and Intensive Care I,”Iuliu Hatieganu” University of Medicine and Pharmacy, Cluj-Napoca, Romania.
She said: “There are reports that not only inhaled or intravenous agents may affect long term outcome after anaesthesia, but also some other anaesthetic interventions as well. Thus opioids, regional anaesthesia/analgesia, NSAIDs and lastly intravenous lidocaine may influence the biology of cancer cells as reported in some studies.”
Prof Ionescu explained that for opioids, most of the studies have shown detrimental effects on cancer cells (proliferation, angiogenesis, migration). However, there are studies showing different results. For regional anaesthesia, most of the clinical studies published so far are retrospective and were focused on overall survival and disease-free interval. Findings are sometimes controversial.
She added: “In recent years a number of studies focused on the effects of lidocaine and other local anaesthetics on cancer cells biology with very interesting results. These results come mainly from in vitro or animal studies, so it is, at the moment, difficult to translate the findings in clinical practice. At present, a number of prospective randominsed controlled trials are underway, focused on the influence of regional anaesthesia and introvenous lidocaine on the outcome of cancer patients undergoing surgery, and their results will shed more light on this topic.”
Dr Tim Wigmore of the Royal Marsden NHS Foundation Trust, London, UK, then followed by saying cancer has become the leading cause of mortality in the developed world and the developing world is not far behind. He said: “Surgery remains the mainstay of treatment, with 80% of patients requiring surgical intervention and given current predictions, this translates to 17 million surgeries per year by 2030. However, there is evidence that the perioperative period is paradoxically linked to an increased risk of metastasis and tumour growth related to stress and immunosuppression.”
He detailed how anaesthesia itself can impact on these factors and recent studies have suggested that the choice of inhalational or intravenous anaesthesia may be crucial, affecting longer term outcomes for patients – laboratory work has shown that both forms of anaesthesia affect the immune system, tumour growth factors and the way that physiological and psychological stress impacts the body in different ways, and that these can result in an overall differential tumorigenic effect.
Dr Wigmore concluded: “This has led to a biologically plausible theory of an adverse (tumour potentiating) role for inhalational agents, which has been largely supported by (albeit low quality) retrospective clinical studies. There are now a number of prospective clinical trials underway that will hopefully shed more light on this and deliver an unequivocal answer.”
The final talk was by Dr William Harrop-Griffiths, Consultant Anaesthetist at Imperial College Healthcare NHS Trust, London, UK
He said: “Continuous improvement in medical care depends upon doctors being prepared to change the treatment that they give. As a professional group, they are naturally conservative, and they often take some convincing that change will benefit patients. Medical evidence from research is sometimes not convincing and often not conclusive.”
The factors that will affect a doctor’s willingness to change will include:
– The amount and quality of evidence supporting the change
– The views of peers about the change
– The costs of change
– The potential risks of the change
– The potential benefits of the change
– The existence of authoritative guidance that supports the change
“The available evidence that anaesthetic technique may affect cancer recurrence after surgery is not convincing,” explained Dr Harrop-Griffiths. “However, the costs of changing technique to one that may be associated with decreased cancer recurrence is small, the risks are few and the benefit is potentially large – even if only one in 100 patients benefits, as cancer is a common disease and its treatment can be expensive.”
He concluded: “I think that now is the time to change anaesthetic techniques for cancer surgery, even though some will – quite reasonably – argue that the evidence is not yet conclusive. It all comes down to this question, which should be asked of all anaesthetists: what anaesthetic technique would you want if you were to have cancer surgery?”