Volatile anesthetics, immune-modulation and cancer biology: What is the story?

Whist there are now numerous studies in which isolated tumour cell lines have been exposed to various anaesthetic agents in a laboratory setting, the issue with these is that they fail to mimic the micro-environment that surrounds tumour cells in the perioperative period and which is responsible for determining cell survival and proliferation, This milieu includes growth factors, immuno-modulators, and pro (and anti-inflammatory) cytokines, all impacting on the complex interplay of local vasculature, lymphatics, and immune and tumour cells.

This study was different – In a randomised, prospective clinical trial, the study team took serum (both at induction and 24hrs post) from 40 patients randomised to undergo open colon cancer surgery with one of two different anaesthetic techniques, either TIVA plus thoracic epidural (PEA), n=20, or inhalational (sevoflurane) plus opioid analgesia (SGA), n=20. The serum was then mixed with human colon cancer cells (LoVO) which had been cultured in vitro in separate experiments to test the effect of the serum on proliferation, migration, apoptosis and cell viability of the LoVo cells.

The team found that serum collected from after 24hrs from the PEA group as compared to the SGA group reduced proliferation, invasion and proportion of viable cancer cells and increased apoptosis. There was no difference in the effect of serum collected before surgery on tumour cell behaviour.

So – What to make of this ? The study adds significantly to our body of knowledge in that it demonstrates an in vitro effect of serum taken in vivo from cancer patients undergoing two different kinds of anaesthesia. What is more, this effect appears to confirm that which we have found in laboratory experiments; Volatile anaesthesia may promote tumour cell proliferation, invasion and metastasis. What it does not tell us is either the mechanism by which this effect occurs or which constituent of the PEA group (epidural or TIVA, or both) is responsible for the relatively beneficial effect seen using the serum of this group of patients. There is much work still to do, but this study is a definite step in the right direction.

Re Stollings, L. M., Jia, L. J., Tang, P., Dou, H., Lu, B., & Xu, Y. (2016) .”Immune modulation by volatile anesthetics”. The Journal of the American Society of Anesthesiologists, 125(2), 399-411.

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