The Influence of Analgesic Modalities on Postoperative Cancer Recurrence

The potential for cancer cells to grow and to metastasize depends on complex interactions between inflammatory signals and pathways, immune cells, and elements of the stromal tissue in which they invade. Related to the nature of many cancers, the probability of recurrence can potentially be quite high for some patients. Immunology, lifestyle modifications, timing of disease, genetics, age, gender, and race are only a handful of ways the likelihood of cancer recurrence can be influenced. The quantity, or density, of certain immunological cells or factors, plays a role in the propagation of cancer cells. Opioids are often used in cancer patients for acute postoperative and chronic pain management. While they can produce significant pain relief, the type of analgesic utilized is important, as it may influence cancer propagation. In this regard, certain opioids have been found to increase T regulatory cells while suppressing NK cell function. Morphine may promote tumor neovascularization and expansion. Fentanyl administration significantly diminishes NK-cells and CD8+ cytotoxic T-cells. In a recent meta-analysis, propofol-based anesthesia improved both cancer-free survival and overall survival. COX inhibitors have also shown promise in persevering cancer immune function, as in literature involving ketorolac and celecoxib. In summary, inhaled anesthesia and opioids may contribute to a pro-tumor metastasis environment also known as cancer propagation; whereas propofol and COX inhibitors may provide a better alternative to reduce cancer recurrence and propagation.