The role of analgesics in cancer propagation.

The treatment of cancer pain is paramount to both medical practitioner and patient in order to maximize quality of life. Cancer pain results from direct tumor effects as well as from surgical and medical treatments. Despite therapeutic advancements, morbidity and mortality in cancer care remains high, often from local recurrence or metastasis. Increasing evidence suggests analgesics affect the cellular milieu of malignant and nonmalignant cells and may influence cancer outcomes by directly stimulating tumor growth and inhibiting immune surveillance. Opioids have been shown to cause immunosuppression and stimulate malignant cells in vitro, though adjunct analgesics may additionally promote tumor cell growth. These results have led many to hypothesize that regional analgesic techniques may offer survival advantages to systemic analgesics. Thus far, the data do not support specific analgesic recommendations for the cancer patient, though ongoing prospective, randomized clinical trials are under way to better characterize the safest analgesic regimens for cancer patients.