Introduction

The majority of cancer patients (approximately 80%) develop pain before they die (1). Pain in cancer patients is often underdiagnosed, and inadequate treatment with opioid analgesics is well documented (2–4). Many factors influence pain management in this patient group. Inappropriate and suboptimal education of physicians and other health care professionals has been identified as the major barrier to adequate opioid use (5,6). In developing countries, a further issue is reduced availability of opioids because of financial limitations and government regulations.

As a result of a major educational effort by a number of organizations, including the World Health Organization, the International Association for the Study of Pain, and the American Society of Clinical Oncology, opioid use has improved significantly in developed countries during the last 15 years (7). The results of such efforts have been quite variable (8). In many regions of the world, however, progress has been made, with opioids being used in higher doses and at earlier stages in palliative care (9). Cancer patients, who now have earlier exposure to opioids and generally have treatment with higher dosages, are better managed than in the past. This highly desirable increase in the use of opioids, combined with increased vigilance, has resulted in increased detection of several side effects, most notably neurotoxicity. With this increase in opioid use and the improvement in identification of adverse effects, management strategies for dealing with these unwanted effects have been developed and augmented.