The Effect of Epidural Fentanyl on Immune Function

Background: For cancer to grow and metastasize, inflammatory and immunologic conditions in the host must be favorable. The perioperative period provides inflammatory and immunologic changes that may be pro-malignant. Anesthetic medications, including the use of opioid medication, may contribute to these changes.

Hypothesis: The investigators hypothesize that perioperative immunologic changes in patients undergoing resection of hepatic colorectal cancer recurrence, as measured by natural killer cell function and cytokine levels, will undergo less alterations in those who receive only epidural bupivacaine, as compared to those who receive epidural bupivacaine and fentanyl.

Methods: In this double blind control trial patients with no extra-hepatic evidence of cancer, undergoing a planned curative resection of hepatic recurrence of colorectal cancer, will be randomized to receive an epidural with bupivacaine and fentanyl, or bupivacaine alone. No other perioperative opioid medication will be given, and post-operative analgesia will be supplemented with acetaminophen and gabapentin. Blood samples and pain ratings using a verbal analogue scale will be obtained preoperatively, immediately and 6 hours postoperatively, and then daily until removal of the epidural catheter. Samples will be analyzed for levels of interleukin 2, 6, 8, 10, 12, 16, 17,TNF-α, TGF α and β, MCP-1, CRP, and NK cell activity. Cytokines will be measured using a suspension bead array immunoassay kit, and NK activity will be measured using flow cytometry of isolated peripheral blood mononuclear cells exposed to the K562 cell line and treated with fluorescent antibodies to intracellular markers of activation. Data will be compared between groups using t-tests, or Mann-Whitney tests as appropriate. To demonstrate a 50% smaller decrease of NK cell activity in the bupivacaine group as compared to the bupivacaine and fentanyl group the investigators will need to randomize a total of 30 patients.