The role of ketamine in the treatment of chronic cancer pain

BACKGROUND AND AIM: Ketamine is a drug used for the induction and maintenance of general anesthesia, for the treatment of postoperative and posttraumatic acute pain, and more recently, for the reduction of postoperative opioid requirements. The main mechanism of action of ketamine is the antagonization of N-methyl-D-aspartate (NMDA) receptors that are associated with central sensitization. In the pathogenesis of chronic pain and particularly in neuropathic pain, an important role is played by the activation of NMDA receptors. Although ketamine is indicated and used for the treatment of chronic cancer pain as an adjuvant to opioids, there are few clinical studies that clearly demonstrate the effectiveness of ketamine in this type of pain. The aim of this study is to analyze evidence-based clinical data on the effectiveness and safety of ketamine administration in the treatment of chronic neoplastic pain, and to summarize the evidence-based recommendations for the use of ketamine in the treatment of chronic cancer pain. METHOD: We reviewed the literature from the electronic databases of MEDLINE, COCHRANE, PUBMED, MEDSCAPE (1998–2014), as well as chapters of specialized books (palliative care, pain management, anesthesia). RESULTS: A number of studies support the effectiveness of ketamine in the treatment of chronic cancer pain, one study does not evidence clear clinical benefits for the use of ketamine, and some studies included too few patients to be conclusive. CONCLUSIONS: Ketamine represents an option for neoplasic pain that no longer responds to conventional opioid treatment, but this drug should be used with caution, and the development of potential side effects should be carefully monitored.