Several medical organizations recently released a joint Clinical Practice Guideline to provide recommendations on opioid conversion in adults with cancer.1 ASCO, together with the Multinational Association of Supportive Care in Cancer (MASCC), American Academy of Hospice and Palliative Medicine, Hospice and Palliative Nurses Association, and Network Italiano Cure di Supporto in Oncologia, convened an Expert Panel to develop these recommendations, which were designed to standardize and improve the safety and efficacy of opioid conversion.
Mellar P. Davis, MD, FCCP, FAAHPM
“About 60% to 70% of people with advanced cancer have pain, and about 20% to 30% of those with limited cancer have pain,” noted Expert Panel Co-Chair Mellar P. Davis, MD, FCCP, FAAHPM, of Geisinger Medical Center.2 “Opioids are frequently used in that population, but 20% to 40% will develop an intolerance or adverse effects to opioids, or the opioids will simply lose their effect for various reasons.”
Opioid conversion or rotation occurs when one opioid is switched for another using the same route or an alternative route of administration, Dr. Davis explained.
For the systematic review of evidence, 208 studies were identified that provided “mixed and inconclusive findings partly related to study design and study quality” regarding the best approaches to opioid conversion. As a result, the MASCC established an Expert Panel with ASCO to review this evidence and used a Delphi technique to establish this guideline, which consists of 58 consensus statements based on 41 international experts and the systematic review.
“This guideline is not the last word, but through the guideline, we are attempting to establish good practice, so people can be safely treated with opioids,” Dr. Davis said. “The guidelines will help oncologists, palliative specialists, hospitalists, and primary care physicians safely switch opioids.”
The recommendations address three areas of opioid conversion: preconversion assessment, conversion strategies, and postconversion assessments.
Preconversion Assessment
“With preconversion assessment, we want to make sure that people are comfortable and competent with changing opioids and routes,” Dr. Davis said. “Poor pain control may not be related to the opioid but [may be] because people aren’t taking the medication due to fear or addiction stigmata associated with opioids, which has become acute with the present opioid epidemic.”
A pain assessment is important before opioid conversion, Dr. Davis said. Not all patients describe their pain intensity by a numerical or visual scale. Some patients may describe pain in relation to their ability to function and complete daily activities.
Clinicians also must be aware of a patients’ organ function, what other medications they are on, what opioids have previously been used, and what their goals are.
“We can also discuss alternatives to conversion,” Dr. Davis said. “If pain is not well controlled, then using adjuvants may be tried as an alternative to opioid conversion. Nondrug therapies, such as radiation for bone metastases, surgery for bowel obstruction, or stenting for visceral pain, may be better than opioid conversion.”
Recommendations for preconversion assessment also emphasize the role of family members and/or caregivers as intrinsic to successful opioid therapy. These informal members of the care team need to be available to monitor patients closely during the days after opioid conversion.
Conversion Strategies
Many considerations factor into the decision for opioid conversion, Dr. Davis said. The choice of a second opioid or route is based on clinical circumstances, opioid availability, physician comfort, and, obviously, published conversion ratios.
Opioid conversion ratios vary greatly across countries and regions. The guideline provides a table with an international consensus of conversion ratios of commonly used opioids and certain second-line opioids. The Expert Panel addressed the use of methadone and its unique pharmacology. Methadone should be prescribed by those experienced with its use, and experts should be aware of several methadone dosing strategies.
There are two statements in the guideline regarding breakthrough pain. One discusses a starting dose. The other recognizes the poor correlation between the around-the-clock effective dose for controlling background pain and the effective dose for breakthrough pain.
The guideline also addresses gaps in the evidence supporting opioid conversion ratios. Not infrequently, two opioids have not been directly compared in clinical trials, and there is a need to use morphine-equivalent daily doses. This may be relatively imprecise or inaccurate, but it may also be all that is available.
Although common practices in opioid conversions included the automatic 25% to 50% of the opioid dose upon conversion for reasons of incomplete cross-tolerance between opioids, this approach was not endorsed by the consensus group. It was thought the conversion ratio is the safe dose that lies between withdrawal and overdose. Although the dose does need to be tailored to the individual, the Expert Panel believed it should not automatically be reduced as a routine practice.
Postconversion Assessment
One of the most important aspects after opioid conversion is that patients be followed closely, according to the guideline. Dr. Davis recommended that family members or informal caregivers be educated about what is being done and what to look for.
Patients should be assessed for pain severity after opioid conversion using a validated scale. However, it is important that any pain severity rating be assessed in comparison to that patient’s personal pain severity goal. Dr. Davis said: “A fair number of people don’t quantify the pain but instead say, ‘This is manageable or tolerable.’” Dr. Davis also emphasized assessing patients’ function in addition to pain intensity to determine whether they can complete tasks that are important to them.
Postconversion monitoring of adverse events is also important. “There may be some symptoms that are a little unusual, such as dysphoria, fatigue, or irritability,” Dr. Davis said. “That may reflect a low-grade withdrawal syndrome.”
Subtle neurotoxic symptoms of toxicity—such as myoclonus nightmares or hallucinations—may also occur. Postconversion adverse events may include new-onset nausea, vomiting, confusion, delirium, scratching, pruritus, and rash. Patients may not complain about these subtle symptoms unless they are queried about them. Dose adjustment should be made based on all these factors.
“The number 1 thing is that you can’t go wrong following someone closely, not only prior to conversion, but particularly during and after,” Dr. Davis said. “I’ve never been disappointed making an extra call, but I have been disappointed in not following people closely enough.”
More than 25 statements that did not meet the threshold for consensus were included in a supplement to the publication. These statements, Dr. Davis said, “help set the stage for further research.”
REFERENCES
1. Davis MP, Davies A, McPherson ML, et al: Opioid conversion in adults with cancer: MASCC-ASCO-AAHPM-HPNA-NICSO guideline. Support Care Cancer 33:243, 2025.
2. Mercadante S, Ferrera P, Villari P, et al: Frequency, indications, outcomes, and predictive factors of opioid switching in an acute palliative care unit. J Pain Symptom Manage 37:632-641, 2009.
Originally published in ASCO Daily News. © American Society of Clinical Oncology. ASCO Daily News, March 19. 2025. All rights reserved.
