This press release highlights the findings of two upcoming studies to be presented in November 2009 at the "Molecular Targets and Cancer Therapeutics" conference, which is a joint meeting in Boston of the American Association for Cancer Research, the National Cancer Institute, and the European Organization for Research and Treatment of Cancer. Evidence is growing that opiate-based painkillers such as morphine can stimulate the growth and spread of cancer cells, including breast cancer cells.

The possibility that opiates influence cancer recurrence has slowly gained support as a result of unrelated studies in which the trend was noticed. In a 2002 palliative-care trial, patients who were administered spinal rather than systemic pain relief were found to survive longer. In another study, cancer patients receiving a selective opiate blocker as part of a compassionate-use protocol survived longer than expected. Two recent retrospective studies demonstrated that breast and prostate cancer patients who were administered local rather than general anesthesia had fewer recurrences. Morphine has been found to increase tumor cell proliferation, inhibit the immune response, and promote angiogenesis in the laboratory. "If these laboratory studies are confirmed clinically," suggests Jonathan Moss, professor of anesthesiology and critical care at the University of Chicago, "the selection of anesthetic technique used during the operative procedure and the possible use of opiate antagonists in the perioperative period may be important."