Opioid Conversion in Adults with Cancer: MASCC-ASCO-AAHPM-HPNA-NICSO Guideline

Dr. Mellar Davis discusses the joint guideline from MASCC, ASCO, AAHPM, HPNA, and NICSO on opioid conversion in adults with cancer. He reviews the limited evidence, and the formal consensus process used to develop the guideline. He shares the key recommendations on pre-conversion assessment, how opioid conversion should be conducted, including opioid conversion ratios, and post-conversion assessment. We touch on gaps and questions in the field and the impact of these new recommendations.

Read the full guideline, "Opioid Conversion in Adults with Cancer: MASCC-ASCO-AAHPM-HPNA-NICSO Guideline" at www.asco.org/supportive-care-guidelines.

TRANSCRIPT

This guideline, clinical tools, and resources are available at http://www.asco.org/supportive-care-guidelines. Read the full text of the guideline in the Supportive Care in Cancer, https://link.springer.com/article/10.1007/s00520-025-09286-z

Brittany Harvey: Hello and welcome to the ASCO Guidelines podcast, one of ASCO's podcasts delivering timely information to keep you up to date on the latest changes, challenges and advances in oncology. You can find all the shows, including this one at asco.org/podcasts.

My name is Brittany Harvey and today I'm interviewing Dr. Mellar Davis from Geisinger Medical Center, lead author on "Opioid Conversion in Adults with Cancer: Multinational Association of Supportive Care and Cancer, American Society of Clinical Oncology, American Academy of Hospice and Palliative Medicine, Hospice and Palliative Nurses Association, Network Italiano Cure di Supporto and Oncologia Guideline."

Thank you for being here today, Dr. Davis.

Dr. Mellar Davis: Thank you. I'm glad to be here.

Brittany Harvey Before we discuss this guideline, I'd like to note that ASCO takes great care in the development of its guidelines and ensuring that the ASCO Conflict of Interest Policy is followed for each guideline. The disclosures of potential conflicts of interest for the guideline panel, including Dr. Davis, who has joined us here today, are available online with the publication of the guideline, which is linked in our show notes.

So then, to dive into the content here, Dr. Davis, can you provide an overview of both the scope and purpose of this guideline on opioid conversion in people with cancer?

Dr. Mellar Davis: This is an important topic in management of cancer pain and this topic came up as a result of a survey that MASCC had done, which involved 370 physicians in 53 countries. They were queried about how they change or convert one opioid to another, which is a common practice, and we found that there was quite a divergence in opioid conversion ratios. To step back a little bit, about two thirds of patients with advanced cancer have moderate to severe pain and most of the time they're managed by opioids. But about 20% or 40% require a switch either because they have an adverse reaction to it or they don't respond to it, or the combination of both. Rarely, it may be that they need a route change, perhaps because they have nausea or vomiting. So, the opioid conversion works basically because of the complexity of the new opioid receptor which has at least four exons to it as a result of that non-cross tolerance between opioids.

As a result of the survey, we convened a group of specialists, 14 international specialists, to look to see if we could develop an international guideline. And we did a systematic review which involved viewing 21,000 abstracts and we came up with 140 randomized trials and 68 non-randomized trials. And after reviewing the data, we found that the data was really not strong enough to provide a guideline. As a result, ASCO, MASCC, the AAHPM, the HPNA and the Italian Group formed a supportive network that allowed us then to do a Delphi guideline based upon ASCO modified criteria for doing Delphi guidelines.

And so we then involved 27 additional international experts informing the guideline to it. And this guideline is then the result of the Delphi process. It consists basically of a pre-conversion ratio recommendations, conversion ratios, which is actually a major contribution of this guideline, and then what to do after converting someone to another opioid. Our target audience was not only oncologists, but also we wanted to target nurses, pharmacists, hospitalists, primary care physicians, patients and caregivers.

Brittany Harvey: I appreciate that background information, particularly on the evidence that is underpinning this and the lack of quality of evidence there, which really transformed this into a formal consensus guideline. We're glad to have all of these organizations coming together to collaborate on this guideline.

So then next I'd like to review the key recommendations. So starting with, what is recommended for pre-conversion assessment?

Dr. Mellar Davis: In regards to pre-conversion, physicians and clinicians need to be aware of pain phenotypes. That is, there are pains that are more opioid refractory than others, such as neuropathic pain, hence, they may be more resistant to the opioid that you're converting to. One needs to be aware of the fact that patients may not be compliant, they're either afraid of opioids not taking what was prescribed, so it's important to query patients about whether they are taking their opioid as prescribed. Occasionally, there are patients who will divert their medication for various reasons. Pain may be poorly controlled also because of dosing strategies that are poorly conceived, in other words, giving only 'as needed' opioids for continuous cancer pain. And there are rare circumstances where an opioid actually induces pain and simply reducing the opioid actually may improve the pain. The other issue may be cancer progression. So that poorly controlled pain or rapidly increasing pain may actually be a result of progressive cancer and changing treatment obviously will be important. And you need to assess the pain severity, the quality of the pain, the radiating localizing effects, which does require not only a physical exam but also radiographic examinations.

But the other thing that's very important in opioid conversions are pain scales with function. A significant number of patients don't quite understand a numerical scale which we commonly use: 0 to 10, with 10 being severe pain and 0 being no pain. They may in fact focus more on function rather than on pain severity or pain interference with daily activities or roles. Sometimes patients will say, "Oh, my pain is manageable," or "It's tolerable," rather than using a numerical scale. Choices of opioids may be based on cost, drug-drug interactions, organ function, personal history or substance use disorder so that one will want to choose an opioid that's safe when converting from one to another. And obviously social support and having caregivers present and understanding the strategy in managing pain will be important.

Brittany Harvey: Thank you, Dr. Davis, for reviewing those pre-conversion assessment considerations and particularly the challenges around some of those.

So, following this pre-conversion assessment, what are the recommendations on how opioid conversion should be conducted?

Dr. Mellar Davis: Opioid conversions are basically the safe dose. People have used the term 'equianalgesia', but the panel and the consensus group felt that that would be inappropriate. So a conversion ratio is the dose at which the majority of patients will not experience withdrawal or adverse effect. It would be the safe dose. Thereafter, the dose will need to be adjusted. So, in converting, that's only the first step in managing pain, the doses need to be adjusted to the individual thereafter. There are a significant number of conversions that are done indirectly, that is that there has not been a study that has looked at a direct conversion from one opioid to another in which one needs to convert through another opioid. We call that a 'morphine equivalent daily dose'. So, most of the time a third opioid is used in the conversion. It allows you then to convert when there hasn't been a direct study that has looked at conversion between those two opioids, but it is less accurate and so one has to be a little bit more careful when using morphine daily equivalents.

We found, and I think this is the major advantage to the guideline, is that commonly used opioids - oxycodone, morphine, hydromorphone - we did establish conversion ratios to which we found in the MASCC guideline they were widely divergent and hope that actually, internationally, they will be adopted. We also found some conversion ratios for second-line opioids. However, we felt also that an opioid like methadone, which has a unique pharmacology, should be left to experts and that experts should know at least several ways of converting from morphine usually to methadone. There is what appears to be a dose-related increased potency of methadone relative to morphine, which makes it more difficult, particularly at higher doses, to have an accurate conversion ratio. Most patients will have transient flares of pain. We came up with two suggestions. One is using a 10 or 15% of the around-the-clock dose for the breakthrough dose, but we also realized that there was a poor correlation between the around-the-clock dose and the dose used for transient flares of pain. And so the breakthrough dose really needs to be adjusted to the individual responses.

There was also a mention of buprenorphine. One of the unique things about buprenorphine is that if you go from high doses of a drug like morphine to buprenorphine in a stop-start dosing strategy, you can precipitate withdrawal. And so one has to be careful and have some experience in using buprenorphine, which can be an effective analgesic.

Brittany Harvey: Yes, I think that the conversion ratios that you mentioned that are in Table 3 in the full guideline are a really useful tool for clinicians in practice. And I appreciate the time that the panel and the additional consensus panel went through to develop these. I think it's also really key what you mentioned about these not being equianalgesic doses and the difficulties in some of these conversions and when people need to really look to specialists in the field.

So then, following opioid conversion, what assessments are recommended post-conversion?

Dr. Mellar Davis: Post-conversion, probably the cardinal recommendation is close observation for response and for toxicity. And I think that probably summarizes the important parts of post-conversion follow up. So assessment should be done 24-48 hours after conversion and patients followed closely. Assessment scales should include patient personalized goals. Now, it used to be in the past that we had this hard stop about a response being below 4 on a 0 to 10 scale, but each patient has their own personal goals. So they gauge the pain severity and their function based upon response. So a patient may function very well at "a severity of 5" and feel that that is their personal goal. So I think the other thing is to make sure that your assessment is just not rote, but it's based upon what patients really want to achieve with the opioid conversion. The average number of doses per day should be assessed in the around-the-clock dose so those should be followed closely. Adverse effects can occur and sometimes can be subtle. In other words, a mild withdrawal may produce fatigue, irritability, insomnia and depression. And clinicians may not pick up on the fact that they may be actually a bit under what patients have or they're experiencing withdrawal syndrome.

It's important to look for other symptoms which may be subtle but indicating, for instance, neurotoxicity from an opioid. For instance, visual hallucinations may not be volunteered by patients. They may transiently see things but either don't associate with the opioid or are afraid to mention them. So I think it's important to directly query them, for instance, about visual hallucinations or about nightmares at night. Nausea can occur. It may be temporary, mild, and doesn't necessarily mean that one needs to stop the second opioid. It may actually resolve in several days and can be treated symptomatically. Pruritus can occur and can be significant. So close observation for the purposes of close adjustments are also necessary. As we mentioned, you want to start them on an around-the-clock of breakthrough dose, but then assess to see what their response is and if it's suboptimal then you'll need to adjust the doses based both upon the around-the-clock and the breakthrough dose or the dose that's used for breakthrough pain. Also looking at how patients are functioning, because remember that patients frequently look at pain in terms of function or interference with their roles during the day. So, if patients are able to do more things, that may, in fact, be the goal.

Brittany Harvey: Thank you for reviewing all of these recommendations across pre-conversion assessment, how opioid conversion should be conducted, including conversion ratios, and what assessments are recommended after opioid conversion. I think it's really important to be watching for these adverse events and assessing for response and keeping in mind patient goals. So, along those lines, how will these guideline recommendations impact both clinicians and people with cancer? And what are the outstanding questions we're thinking about regarding opioid conversion?

Dr. Mellar Davis: I think it's important to have a basic knowledge of opioid pharmacology. There's, for instance, drugs that are safer in liver disease, such as morphine, hydromorphone, which are glucuronidated. And there are opioids that are safer in renal failure, such as methadone and buprenorphine, which aren't dependent upon renal clearance. I think knowing drug-drug interactions are important to know. And sometimes, for instance, there may be multiple prescribers for a patient. The family physician's prescribing a certain medication and the oncologist is another, so being aware of what patients are on, and particularly over-the-counter medications which may influence opioid pharmacokinetics. So complementary medications, for instance, being aware of cannabis, if patients are using cannabis or other things, I think, are important in this.

There are large gaps and questions and that's the last part of the guideline that we approach or that we mentioned that I think are important to know. And one is there may be ethnic differences in population in regards to clearance or cytochrome frequencies within communities or countries, which may actually alter the conversion ratios. This has not been explored to a great extent. There's opioid stigmata. So we are in the middle of an opioid crisis and so people have a great fear of addiction and they may not take an opioid for that reason, or they may have a relative who's been addicted or had a poor experience. And this may be particularly true for methadone and buprenorphine, which are excellent analgesics and are increasingly being used but may in fact have the stigmata.

There are health inequalities that occur related to minority groups that may in fact not get the full benefit of opioid conversions due to access to opioids or to medical care. Age, for instance, will cause perhaps differences in responses to opioids and may in fact affect conversion ratios. And this may be particularly true for methadone, which we have not really explored to a great extent. And finally, the disease itself may influence the clearance or absorption of an opioid. So for a sick patient, the opioid conversion ratio may be distinctly different than in a healthy individual. This is particularly seen with transdermal fentanyl, which is less well absorbed in a cachectic patient, but once given IV or intravenously has a much longer half life due to alterations in the cytochrome that clears it. And so conversion ratios have frequently been reported in relatively healthy individuals with good organ function and not that frequently in older patient populations. So just remember that the conversion ratios may be different in those particular populations.

Brittany Harvey: Yes. So I think a lot of these are very important things to consider and that managing cancer pain is key to quality of life for a lot of patients and it's important to consider these patient factors while offering opioid conversion.

I want to thank you so much for your work to review the existing literature here, develop these consensus-based recommendations and thank you for your time today, Dr. Davis.

Dr. Mellar Davis: Thank you.

Brittany Harvey: And thank you to all of our listeners for tuning in to the ASCO Guidelines podcast. To read the full guideline, go to www.asco.org/supportive-care-guidelines. You can also find many of our guidelines and interactive resources in the free ASCO Guidelines app available in the Apple App Store or the Google Play Store. If you have enjoyed what you've heard today, please rate and review the podcast and be sure to subscribe so you never miss an episode.

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