Oxycodone and the challenge of neuropathic cancer pain: a review

In order to evaluate the potential role of oxycodone in cancer pain management, neuropathic cancer pain was selected as a model for difficult pain syndromes. A nonsystematic, yet exhaustive, review of the literature provided the relevant evidence for the discussion. Ten randomized controlled trials (RCTs) and 5 open-label studies on oxycodone and cancer pain, 3 RCTs and 1 open-label study on oxycodone and neuropathic pain, and 2 RCTs on oxycodone and visceral pain were identified and reviewed. Additionally, 5 basic research studies that contributed to our knowledge of the specific mechanisms of action of oxycodone were also reviewed. Finally, recent evidence-based reviews of RCTs on neuropathic pain were selected (6 reviews), and specific RCTs on neuropathic cancer pain were also identified (2 trials). The review of the literature shows that the management of neuropathic cancer pain has changed dramatically in the last few years thanks to new approaches and novel drugs. The vast majority of these new drugs have been proven to be useful in 'benign' neuropathic pain syndromes. The intrinsic difficulties in performing RCTs in cancer pain have traditionally justified the acceptance of drugs already known to be effective in benign neuropathic pain, in spite of insufficient evidence in malignant neuropathic pain. Therefore, a case is made for the development of specific guidelines for the management of both simple and complex cases of neuropathic cancer pain. An example of one of such clinical guidelines is provided, in which the role of oxycodone is particularly relevant given the existing evidence.