Background: Opioids are the main drug treatment for moderate to severe cancer pain. Dose limiting side effects may appear during dose titration requiring opioid rotation (OR). The frequency of OR is not well described. The objective of this study was to determine the frequency and indications for OR in cancer pain.

Methods: This prospective observational study enrolled consecutive new patients seen by a Palliative Medicine service over a ten-week period. Demographic data, primary cancer sites, extent of disease, performance status, current opioid and route, reasons for rotation, the opioid chosen for rotation and route of administration were recorded on a standardized data collection form. Patients were followed until death or for six months.

Results: Of 238 patients studied, 78% (186) had cancer and 62% (116/186) of those with cancer had pain. Moderate to severe pain was experienced by 67% (77/116) of them. Forty-two percent (49/116) underwent one or more OR either after initial evaluation or during the course of follow-up; 53% (26/49) were on oxycodone prior to OR; and 47% (23/49) were rotated to morphine. Twelve percent underwent a second, 3% a third, and 2% a fourth OR. A total of 69 OR were done in 116 patients. Forty-seven percent (23/49) had more than one reason for OR. The most common reason for OR was inadequate analgesia in 25 (51%) followed by severe side effects in 21 (43%). Cost, organ failure, neuropathic pain, route and dosing convenience were among the other reasons for OR.

Conclusion: OR was required in 42% of cancer patients given opioids for pain over a six month period usually because of poor pain control.