Although acupuncture has been practiced for millennia, it has come under scientific investigation only recently. To date, most studies and clinical trials of the mechanisms and efficacy of acupuncture in cancer management have been carried out in China. In 1976, however, the U.S. Food and Drug Administration (FDA) classified acupuncture needles as investigational devices (Class III) (www.fda.gov). This resulted in a number of research studies on the effectiveness and safety of acupuncture. In November 1994, the Office of Alternative Medicine (the predecessor of the National Center for Complementary and Alternative Medicine) at the National Institutes of Health (NIH) sponsored an NIH-FDA workshop on the status of acupuncture needle usage. Two years later, the FDA reclassified acupuncture needles as medical devices (Class II) without, however, giving specific indications for their use. In 1997, NIH held a Consensus Development Conference on Acupuncture to evaluate its safety and efficacy. The 12-member panel concluded that promising research results showing the efficacy of acupuncture in certain conditions have emerged and that further research is likely to uncover additional areas in which acupuncture intervention will be useful. The panel stated that "there is clear evidence that needle acupuncture treatment is effective for postoperative and chemotherapy N/V." It also stated that there are "a number of other pain-related conditions for which acupuncture may be effective as an adjunct therapy, an acceptable alternative, or as part of a comprehensive treatment program," and it agreed that further research is likely to uncover additional areas in which acupuncture intervention will be useful.
These actions by the FDA and NIH have resulted in the establishment of a number of active programs of research into the mechanisms and efficacy of acupuncture, much of which is, or is potentially, relevant to cancer management. To date, the most extensively investigated aspect of these mechanisms has been the effect of acupuncture on pain management. The NIH Consensus Panel concluded that "acupuncture can cause multiple biological responses," local and distal, "mediated mainly by sensory neurons...within the central nervous system." Acupuncture "may also activate the hypothalamus and the pituitary gland, resulting in a broad spectrum of systemic effects," including "alterations in peptides,hormones and neurotransmitters and the regulation of blood flow." Recent studies show the effect of acupuncture on chronic inflammatory pain.[22,23] Evidence suggests that acupuncture operates through the autonomic nervous system to balance the sympathetic and parasympathetic systems and suggests that the anti-inflammatory effects of acupuncture are mediated by its electrophysiologic effects on neurotransmitters, cytokines, and neuropeptides.[23,24,25,26,27,28,29,30,31,32] Reviewed in  Many studies provide evidence that opioid peptides are released during acupuncture and that acupuncture analgesia is mediated by the endogenous opioid system.[33,34]