Effect of anaesthetic technique on immune cell infiltration in breast cancer: a follow-up pilot analysis of a prospective, randomised, investigator-masked study.

BACKGROUND: Live animal studies using an inoculation model of breast cancer indicate that anaesthetic drugs and techniques differentially affect cancer metastasis, inversely related to Natural Killer (NK) cell and T lymphocyte levels. Clinical histological studies demonstrate that the distribution of these immune cells and macrophages in intra-tumoral cancer tissue can predict prognosis and response to therapy. No study has evaluated whether the anaesthetic technique influences human breast cancer immune cell infiltration. MATERIALS AND METHODS: Excised breast cancer specimens from patients previously enrolled in an ongoing, prospective, randomised trial (NCT00418457) investigating the effect of anaesthetic technique on long-term breast cancer outcome were immunohistochemically stained to enable a colour deconvolution technique to summate marked immune cell infiltration: CD56 (NK cells), CD4 (T helper cells), CD8 (T suppressor cells) and CD68 (macrophages). Patients were randomised to receive either a propofol-paravertebral anaesthetic with continuing analgesia (PPA, n=12) or a balanced general anaesthesia with opioid analgesia (GA, n=16) for 24 h postoperatively. Investigators were masked to group allocation. RESULTS: Normalised positive intensity values, (median (interquartile range (IQR)), for CD56 were lower in GA121 (116-134) versus 136 (132-142), p=0.015. CD4 was also lower in GA10.9 (5.5-27.8) versus PPA 19.7 (14.4-83.5), p=0.03 but CD8 5.5 (4.0-9.75) versus 13.0 (5.0-14.5) respectively, p=0.24 and CD 68 infiltration 5.8 (3.25-8.75) versus 8.0 (3.0-8.75), p=0.74 were not significantly different. CONCLUSION: PPA induces increased levels of NK and T helper cell infiltration into breast cancer tissue compared with GA but not T suppressor cells or macro phages. This is consistent with the hypothesis that the anaesthetic technique may affect perioperative immune function conducive to resisting breast cancer recurrence and metastasis.