Cancer-induced bone pain: spinal cord mechanisms and traditional Chinese medicine treatment

Abstract

Cancer-induced bone pain (CIBP) is a severe, intolerable, and complex pain condition caused by the primary bone tumor or bone metastasis. CIBP is a combination of complex pain states such as persistent dull pain, spontaneous pain, and mechanical allodynia. Its unique breakthrough pain makes patients suffer because of its unstable onset time and extremely strong pain. The mechanisms of CIBP involves inflammatory, neuropathic factors and specific peripheral local tumor destruction. Approximately 75% of patients with advanced cancer have experienced CIBP. With the survival time of patients with cancer being prolonged, only half of the CIBP can be well controlled. To develop more effective drugs and improve the quality of life of patients with CIBP, it is particularly urgent to extensively study the complex mechanisms of the occurrence and development of CIBP as well as to uncover new targets for developing new analgesics. The spinal cord is the primary center of nociceptive signal processing. During CIBP, unique neurobiochemical changes occur in the spinal cord level. Therefore, the study on the spinal cord level mechanisms of CIBP facilitates the development of efficient and accurate treatment of CIBP. During the development of CIBP, the central sensitization caused by the enhanced information transmission of “neuron glial cells” in the spinal cord is closely related to the central nervous inflammation (mainly activated by glial cells such as astrocytes and microglia). CIBP belongs to the category of “arthralgia” or other diseases in traditional Chinese medicine (TCM). The pathogenesis is mostly the empirical evidence of “impassability leads to pain” and the deficiency syndrome of “dishonor leads to pain”, which is often mixed with deficiency and reality. Treatment should be based on the basic principles of “supporting righteousness and eliminating evil” and “treating both the symptoms and the root cause”. TCM has a good analgesic effect in the treatment of CIBP, of based on syndrome differentiation and treatment tonic agents, rational blood agents, Qi-regulating agents, are mostly used in the selected of prescriptions, with effects as dispelling wind dampness, promoting blood circulation, and removing blood stasis, tonifying deficiency drugs and so on. With the development of integrated traditional Chinese and Western medicine research, the specific mechanisms of TCM to alleviate CIBP is gradually clear. This review summarizes the basic research on the spinal cord mechanism of CIBP and internal treatment of CIBP with TCM in recent 10 years.