How regional analgesia might reduce postoperative cancer recurrence

Cancer surgery still represents the main treatment indication for a large variety of cancers. At the time of surgery, an unknown number of dormant tumors may already exist distal to the primary cancer. At the same time, a large number of malignant circulating cells are released into the blood stream due to tumor manipulation. The immune system plays an important role in clearing cancer cells, thus a competent immune system is required to avoid further progression of the minimal residual disease in the perioperative period. Unfortunately, volatile anesthetics, opioids and surgical stress cause significant immune depression. At the humoral level, there is a predominant increase in pro-tumor cytokines such as interleukin 4 and 10. At the cellular level, there is impairment in the function of natural killer cells. An alternative, to a volatile-opioid general anesthetic technique is the use of regional anesthesia and analgesia, since this reduces the consumption of volatile anesthetics, opioids and diminishes surgical stress. Thus, it has been speculated that regional anesthesia may improve cancer recurrence when used during " curative" surgery. Although, animal experiments suggest that the use of regional anesthesia may reduce further tumor growth; to date, there is no solid clinical evidence to suggest that the use of regional anesthesia or analgesia may reduce cancer recurrence. Unfortunately, all evidence comes from retrospective studies.