Early immunological events in postoperative epidural/intravenous analgesia after colorectal cancer resection

Background and purpose:Postoperativepainisacommonconsequence of extensive surgery with activation of the nervous system for the implementation of pain (nociceptive system), tissue injury or inflammation. As a result of tissue injury, many different mediators are released from damaged tissues, immunocompetent cells, sympathetic and sensory fibers which directly or indirectly activate nociceptors. Postoperative pain leads to suppression of the immune system, including reduced activity of NK cells, cytotoxic T lymphocytes and macrophages.