Pain resulting from the spread of cancer to skeletal bone is the most common physical symptom in cancer patients and can severely disrupt their quality of life. Standard opioid treatments used to ease the pain can often cause serious side effects. Electroacupuncture (acupuncture combined with electrical stimulation) has been used to treat cancer pain; however, the existing data on its efficacy and how it works are unclear. In a recent study, NCCAM-funded researchers at the University of Maryland investigated the effects of electroacupuncture on cancer pain in rats and also looked at the underlying biomechanisms.
The researchers injected prostate cancer cells into the tibia (shinbone) of rats to induce cancer in the bone, gave them either electroacupuncture or sham electroacupuncture, and then subjected them to various pain tests. The results showed that compared with the sham control, electroacupuncture significantly reduced cancer-induced bone pain.
The researchers also examined the rats' spinal cords to see whether electroacupuncture affected chemical processes thought to play a role in pain. They found that compared with the sham control, electroacupuncture inhibited up-regulation of two substances involved in these processes: spinal cord preprodynorphin mRNA and dynorphin. In a separate experiment, they found that injection of an antiserum against dynorphin also inhibited cancer-induced pain in the rats.
The researchers concluded that electroacupuncture eases cancer pain in rats, at least in part by inhibiting spinal dynorphin. They note that their findings support the clinical use of electroacupuncture in the treatment of cancer pain.
Zhang RX, Li A, Liu B, et al. Electroacupuncture attenuates bone cancer-induced hyperalgesia and inhibits spinal preprodynorphin expression in a rat model. European Journal of Pain.; 12(7):870–878.2008