OBJECTIVETo investigate the effects of different anesthesia methods on immune surveillance and tumor metastasis in tumor-bearing rats.

METHODSSeventy-two Fischer 344 rats were randomly assigned into 3 equal groups and anesthetized for 1 h with ketamine (group K), propofol (group P), or neuraxial block (group B). All the rats were subjected to laparotomy followed by intravenous injection of MADB106 tumor cells, and 24 h after the injection, the number and activity of circulating CD3(+), CD4(+), CD8(+), and D4(+)/CD8(+) lymphocyte subsets and NK cellèCD161a(+)éwere assessed. Three weeks later, the lung metastases were counted.

RESULTSCompared with those in group B, the numbers of CD3(+), CD4(+), CD8(+), and CD161a(+) lymphocytes and the activity of circulating NK cells were significantly reduced, and the lung metastases of MADB106 increased significantly in groups K and P (P<0.05 or 0.01 ). The activity of immune surveillance in group K was significantly lower than that in group P except for CD8(+) cells, and the tumor metastases in group K increased significantly in comparison with those in group P (P<0.05 or 0.01).

CONCLUSIONNeuraxial block provides protection of the activity of immune surveillance and reduces tumor metastases in tumor-bearing rats compared with general anesthesia.