Dr. Ilana Braun and Dr. Eric Roeland join us on the ASCO Guidelines podcast to discuss the latest evidence-based recommendations on cannabis and cannabinoids in adults with cancer. They discuss nonjudgmental patient-clinician communication, the relatively narrow cancer-related indications for which there is actionable clinical evidence for cannabis and/or cannabinoids, and key information for adults with cancer and their clinicians. Dr. Braun and Dr. Roeland also review the limited evidence regarding cannabis and cannabinoid use in adults with cancer and the outstanding questions and importance of research in this area. Read the full guideline, "Cannabis and Cannabinoids in Adults with Cancer: ASCO 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 and review authors' disclosures of potential conflicts of interest in the Journal of Clinical Oncology,

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

My name is Brittany Harvey, and today, I'm interviewing Dr. Ilana Braun from Dana-Farber Cancer Institute, and Dr. Eric Roeland from Oregon Health & Science University, co-chairs on "Cannabis and Cannabinoids in Adults with Cancer: ASCO Guideline."

Thank you both for being here Dr. Braun and Dr. Roeland.

Dr. Ilana Braun: Thanks so much for having us, Brittany.

Dr. Eric Roeland: Thanks, Brittany.

Brittany Harvey: Then, just before we discuss this guideline, I'd like to note that ASCO takes great care in the development of its guidelines and ensures 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. Braun and Dr. Roeland, who have joined us here today, are available online with the publication of the guideline in the Journal of Clinical Oncology, which is linked in the show notes.

Then to jump into the content of this guideline, first, Dr. Roeland, could you give us an overview of both the scope and purpose of this guideline?

Dr. Eric Roeland: Sure, Brittany. I think it's important for everyone to recognize just how common the issue of cannabis or cannabinoid use is amongst people living with cancer. And I think clinicians in academia as well as through community sites, we are asked about the use of cannabis on a daily basis. And so our target audience is really to focus on clinicians providing care to adults with cancer, but also the health systems in which we work because this is a very complex issue, as well as the people living with cancer and their caregivers, as well as researchers dedicated to this field.

Brittany Harvey: So as you mentioned, this is a complex issue, and I'd like to review the key recommendations of this guideline. This guideline provides recommendations across three clinical questions that the expert panel targeted. So, starting with the first question, what is recommended for patient-clinician communication regarding cannabis or cannabinoids?

Dr. Ilana Braun: Given the high prevalence of medicating with cannabis or cannabinoids that Eric references, somewhere in the neighborhood of 20% to over 40% of adults with cancer consume cannabis products, ASCO's guideline offers the following common-sense, good practice statement: In the clinic, providers should routinely and non-judgmentally inquire about cannabis consumption or consideration of cannabis, and either guide care or direct adults with cancer to appropriate resources. In other words, the guideline works to fully destigmatize this conversation. The guideline goes on to offer suggestions for taking a cannabinoid and cannabis history. This includes the goals of use, how the products are sourced, what formulations are being used (including the ratios of active ingredients like THC and CBD), the inactive ingredients (for instance coconut oil), whether it is herbal or synthetic, and whether the product is pharmaceutical grade or non-pharmaceutical grade. And then other questions like routes of administration, dosing schedules, perceived benefits and risks, and whether the products are being used adjunctively or as a replacement for standard treatments. It is also probably important to query potential contraindications, such as a history of cannabis use disorder or psychosis.

Brittany Harvey: Thank you for reviewing those good practice statements. Those are key for non-judgmental communication and taking an accurate and complete history.

So following those statements, the expert panel next addressed the question: Does use of cannabis and/or cannabinoids by adults improve cancer-directed treatment? What recommendations did the expert panel provide for this section?

Dr. Eric Roeland: When we think about the use of cannabis or cannabinoids in treating the underlying cancer, it's incredibly important to recognize the excitement that patients and clinicians have around the potential promise. Much of this data is generated from preclinical models. However, when we're engaging patients consuming cannabis or cannabinoids to augment their cancer-directed treatment, we could find no evidence to support its use. And so we do not recommend that patients be using it to augment treatment, nor do we recommend that patients should be using it instead of their cancer-directed therapy. And I think this is a major challenge for multiple oncologists, where their patients may be using these with a goal of treating their cancer, and then present with very advanced cancer and/or multiple poorly controlled symptoms.

Dr. Ilana Braun: And I think that there are some areas of particular concern. For instance, there were two oncologic cohort studies that suggest that cannabis, which we know is an immune modulator, may actually worsen immunotherapy outcomes. These outcomes included median time to progression and overall survival. There are obvious limitations of preliminary observational data, and we now need to gather prospective, gold-standard data. But for the time being, the guideline recommends that clinicians should advise against adults receiving immunotherapy from medicating or considering medicating with cannabis and cannabinoids. And then I think there are some additional reasons for concern. First of all, this type of therapy tends to be very expensive and not covered by insurance and there are some risks for drug-drug interactions, in terms of pharmacodynamic ones, Cannabis may exacerbate neuropsychiatric side effects of opioids and even benzodiazepines. In terms of pharmacokinetic drug-drug interactions, it's not a particularly risky substance, but there are three to be wary of in particular: warfarin, buprenorphine, and tacrolimus all have high-risk interactions with cannabinoid products.

Brittany Harvey: I appreciate you both for reviewing these recommendations and evidence regarding the use of cannabis and/or cannabinoids regarding cancer-directed treatment.

So then the last clinical question, Dr. Braun, what is recommended regarding use of cannabis and/or cannabinoids in managing cancer treatment-related toxicities and/or symptoms?

Dr. Ilana Braun: The first thing to make clear is that high-quality clinical evidence evaluating the utility of cannabis and cannabinoids for adults with cancer is limited as Eric has said. The evidence that does exist weakly supports a practice of using cannabis and cannabinoids to address refractory chemotherapy-induced nausea and vomiting when standard treatments have failed. For other potential oncologic indications, like management of cancer-related pain, there is weak, negative, conflicting, or no evidence. But that being said, a 2017 monograph published by the National Academies of Science, Engineering, and Medicine concluded that there is substantial evidence that cannabis is an effective treatment for chronic non-cancer pain, and I'm sad to say, that chronic non-cancer pain happens too in adults with cancer.

Brittany Harvey: Thank you for reviewing those recommendations as well.

So you've both touched on this a little bit in that patients are often asking clinicians for recommendations regarding cannabis and/or cannabinoids, but in your view, what is the importance of this guideline, and what should clinicians know as they discuss these recommendations with their patients?

Dr. Eric Roeland: Probably one of the most important points is for clinicians to ask and to be open and to create a space where our patients are telling us about what they're using. I think we've all had patients that we've been surprised that have been using cannabis or cannabinoids in conjunction with other medications that may increase the risk of unwanted side effects or risks, including sedation or falls. I also find it challenging that many patients are receiving recommendations for the use of cannabis or cannabinoids directly from friends or family instead of through their medical providers. Therefore, I think one of the very first things is to just make sure that you're asking about it and then inquiring what the goal of their use is.

When we talk about the use of cannabis, we also need to recognize the difference between the available data that can guide us in evidence-based recommendations, as well as the enthusiasm and available access that patients have to cannabis that has really outpaced our ability to research it. So it's important to recognize these tensions that we're living with in clinic day-to-day.

Brittany Harvey: Absolutely. Those points are key for clinicians as they discuss this complex issue with their patients.

Following that, how will these guideline recommendations affect adults with cancer?

Dr. Ilana Braun: One really important takeaway from these guidelines is that they clearly state that cannabis and cannabinoids are medicinal, and for a medical community to clearly articulate this point is notable. I suspect they will provide encouragement, legitimacy, confidence, and even a script to oncology clinicians who were previously reticent to inquire, document, and provide clinical recommendations around non-pharmaceutical cannabis and cannabinoids. It may have a similar effect even at the institutional level in terms of supporting these practices. At the same time, I suspect they will encourage those who are recommending oncologic use of cannabinoids and cannabis for myriad cancer-related indications to adopt a more circumscribed approach. The reason I say this is that the cancer-related indications for which there is actionable clinical evidence at this time are quite narrow. So all this to say, I believe these guidelines will lead to greater transparency around cannabis decision-making in the clinic, as Eric mentions, but also lead to a possible narrowing of indications for which cannabis is clinically recommended.

Dr. Eric Roeland: Another major role of the use of these guidelines in clinical care is informing clinicians and patients about cannabis. Cannabis has been used by humans as a plant for thousands of years, and although it's a very complex plant with hundreds of parts, the two parts that researchers have studied most are delta nine-tetrahydrocannabinol, or THC, and cannabidiol, or CBD. In rough terms, THC can cause a high feeling, while CBD typically does not. And there are multiple types of products that have different ratios of THC and CBD. So it's critical for people to understand what those ratios are, how many milligrams of those things there are, as well as what are the programs within your region to measure or quantify what's actually in the products you're consuming.

If a person with cancer medicates with cannabis, most oncologists would prefer that they use it by mouth, such as an edible, rather than inhaling or smoking cannabis given concerns about potential impact on lung function. One challenge when consuming cannabis by mouth is that it can take up to two hours to have its full effect. So patients should be very careful not to take too much or to stack their doses, which can cause sedation, confusion, and even increase the risk of falls. Whereas when patients are consuming cannabis by breathing in a smoke or vapor, they typically feel the effects almost right away, which is why patients sometimes prefer smoking or vaping as their preferred route of administration.

Brittany Harvey: Understood. Definitely. We hope these guidelines provide key information and clarity for both adults with cancer and their clinicians.

So then, finally, you've both mentioned that there is limited evidence regarding cannabis and cannabinoid use in adults with cancer. So what are some of the outstanding questions regarding cannabis and cannabinoids in cancer care?

Dr. Eric Roeland: Thanks, Brittany. I think the questions also align with priorities for future research, and we need to recognize that the lack of evidence aligns with some of the challenges of funding research in this space. However, ongoing future research priorities include what is the nature of healthcare disparities pertaining to medical cannabis use by adults with cancer, and what are effective means to address these disparities? We also wonder, what are the optimal strategies to maximize communication in the oncology clinic regarding medical cannabis and/or cannabinoid use? And when we're thinking about cannabis and/or cannabinoids for cancer treatment specifically, we still need to know do cannabis and/or cannabinoids possess clinically meaningful anticancer activity in humans. We also need to understand what are the drug-drug interactions with our standard-of-care cancer treatments, including cytotoxic chemotherapy, targeted therapy, immunotherapy, radiation, and combinations of all the above. We also are wondering what the effect of cannabis and/or cannabinoids on outcomes in adults with cancer receiving some of our newer therapies, including antibody-drug conjugates and some of our newer vaccine therapies.

Dr. Ilana Braun: I might add that collating the existing research as the guideline did is a very good first step and should serve to highlight where the gaps in knowledge lie. This guideline discusses some of the unique challenges to conducting cannabis and cannabinoid research, including limitations in funding source and study drug, red tape procedures, and issues around legalization. I believe it will take a group of highly determined and creative researchers to move the needle forward in this area, but we must.

Brittany Harvey: Definitely. Thank you both so much for all of your work developing this guideline and creating these evidence-based recommendations. And thank you for taking the time to come on the podcast today and teach us all a little bit more about cannabis and cannabinoids in cancer care. And thank you for your time, Dr. Braun and Dr. Roeland.

Dr. Ilana Braun: Thanks so much, Brittany.

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, which is 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.

The purpose of this podcast is to educate and inform. This is not a substitute for professional medical care and is not intended for use in the diagnosis or treatment of individual conditions.

Guests on this podcast express their own opinions, experience, and conclusions. Guest statements on the podcast do not express the opinions of ASCO. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement.

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