What People With Cancer Should Know About Cannabis and Cannabinoids

March 13, 2024
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ASCO recently published a clinical practice guideline on cannabis and cannabinoids for adults with cancer. This podcast covers what patients should know about cannabis, cannabinoids, and cancer.



ASCO: You’re listening to a podcast from Cancer.Net. This cancer information website is produced by the American Society of Clinical Oncology, known as ASCO, the voice of the world's oncology professionals.

The purpose of this podcast is to educate and to 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. Guests’ statements on this 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. Cancer research discussed in this podcast is ongoing, so data described here may change as research progresses.

Greg Guthrie: Hi everyone, I'm Greg Guthrie, a member of ASCO's patient education content team, and I'll be your host for today's podcast. ASCO is the American Society of Clinical Oncology, and we're the world's leading professional organization for physicians and oncology professionals caring for people with cancer. Today we're going to be talking about what patients should know about cannabis, cannabinoids, and cancer. ASCO recently published a clinical practice guideline on cannabis and cannabinoids for adults with cancer.

I'm happy to have 2 of the co-chairs from the committee that developed this guideline as our guests today. Dr. Ilana Braun is an associate professor at Harvard Medical School. Thanks for joining us, Dr. Braun.

Dr. Ilana Braun: Thanks so much for having me.

Greg Guthrie: It's a pleasure to have you here today. And Dr. Eric Roeland is an associate professor of medicine at Oregon Health and Science University. Welcome Dr. Roeland.

Dr. Eric Roeland: Thanks, Greg.

Greg Guthrie: Great. So before we begin, I want to note that neither Dr. Braun nor Dr. Roeland have any relationships to disclose related to this podcast, but you can find their full disclosures in this podcast's show notes.

So let's start with the fundamental question about this discussion, and that is what is a clinical practice guideline and how does it help guide cancer care? Dr. Roeland, can you start with this?

Dr. Eric Roeland: Of course, yeah. A clinical practice guideline describes the best practices or what clinicians call the “standard of care” with regard to a specific topic. So this is kind of the blueprint that clinicians use to guide their practice when taking care of people with cancer. And the American Society of Clinical Oncology clinical practice guideline on the use of cannabis and/or cannabinoids summarizes the best available data collected specifically from humans in clinical trials, and we combined that with a multi-disciplinary panel of expert opinion.

Greg Guthrie: Yeah, I think it's really important to always remember that best evidence comes from research in humans as well as from clinical expertise. So it's the best recommendations that we can have to support cancer care.

Dr. Eric Roeland: Greg, I also think it's very important to understand that there are different places that we gain knowledge in research. One is specifically when we are trying to figure out how a drug works, and we will test that in what we call “preclinical models,” which is usually within animals. And then, once we’ve determined safety and efficacy, then we start taking that information and approach studies in humans. And so when our listeners are learning about new data in the use of cannabis or cannabinoids, I encourage everyone to always stop and ask, is this data coming from the animals or is this from humans?

Greg Guthrie: That's such an important point. And I think it's so essential to always look for that piece of evidence whenever you're reading about scientific advances. Alright, so let's take a moment to talk about what it means when we say cannabis and cannabinoids. Dr. Braun?

Dr. Ilana Braun: Cannabis, which is better known as marijuana, is a plant that humans have turned to for thousands of years as a medicine, in manufacturing—for instance, in the making of rope­—and for enjoyment.

It's often mistakenly viewed as having one main ingredient, tetrahydrocannabinol, or THC, but it actually has more than 300 ingredients that act in the body. Some of those ingredients are referred to as cannabinoids. There are 2 cannabinoids of greatest interest, THC, which I just mentioned, and CBD, cannabidiol. THC is responsible for the high feeling some people experience with cannabis. CBD is not.

Currently in the U.S., some cannabis products containing these cannabinoids can be sourced at the pharmacy, others at cannabis dispensaries, and some through more informal means.

Greg Guthrie: That's great. Thank you for that definition here as we continue this discussion. So what do people with cancer typically think cannabis and cannabinoids will do to help them? Dr. Roeland?

Dr. Eric Roeland: Well, it's a great question, Greg, because in clinic, when patients and their loved ones express interest in either starting cannabis or cannabinoids or are currently using them, I always want to explore what their goal of use is. And interestingly, the goals of use are far-reaching. And I have heard everything from, to help with everything, to cure my cancer. And so it's incredibly important to understand why people are reaching towards these products, to understand what their goals are. If they're focused on using this to treat the underlying cancer, or instead of standard cancer therapies, we have grave concerns about this approach. And it may lead to worse outcomes of your cancer.

However, if cannabis or cannabinoids are being used to help with controlling some symptoms during their cancer treatment, it may be helpful. And especially in one particular case where people have really bad nausea and vomiting that persists despite our best medicines to prevent it.

Greg Guthrie: Thank you for that, Dr. Roeland. Dr. Braun, did you have anything to add?

Dr. Ilana Braun: Maybe I will just point out that decisions on what to target with cannabis are often made through trial and error or in consultation with dispensaries, but not as much as I would prefer in consultation with clinical teams.

Dr. Eric Roeland: So I would also add that it's incredibly important to bring these topics up with your clinical team because although cannabis and cannabinoids are considered safe by many because they're quote “natural,” it's important to recognize that they actually can interact with many of the other medications that you're already taking.

For example, patients with cancer might be experiencing really bad pain or anxiety and taking things like opioids or benzodiazepines. And when you combine that with cannabis, it can prolong some of the effects of sedation or confusion. I'd also like to point out that this is not a time where people want to try cannabis for the first time, when they are weak and/or experiencing poor appetite and higher risk of falls. This is not the best time to be trying cannabis or cannabinoids without clear guidance from the clinical care team.

Greg Guthrie: Do you find in writing this guideline and through your clinical experience that most people who are asking about cannabis and cannabinoids, that they already have been trying to use it or are considering it? Because there's a difference there, right? What goal are they looking for, and do they already have a predetermined assumption about what's going to happen with these?

Dr. Eric Roeland: You know, Greg, as clinicians, we talk about a lot of hard stuff. We talk about challenges in terms of health care, access to care, cultural differences, financial toxicity. And it's so fascinating to me that we don't talk about something as simple as whether or not patients are using cannabis. And the reality is that when patients actually bring it up in clinic, I would say that most times they're already using it and are just simply asking for some advice on how to use it safely and effectively. So once I decided to lean in on this topic and create a space for patients and their loved ones to bring it up in clinic, I have found that it's brought up during most clinical encounters.

Greg Guthrie: Fascinating. And so that's likely why the first recommendation of this guideline addresses the importance of communication between doctors and patients on this topic, correct?

Dr. Eric Roeland: Yes, absolutely. I think that doctors are reticent to talk about this topic because of concerns around legal issues, which can be highly varied across the country. And Dr. Braun can speak to this more.

Dr. Ilana Braun: Yeah, so in order to offer the very best care possible, I think that medical teams should know about all the medicines and supplements a person is taking. And this includes cannabis and cannabinoid products. Why? Well, because, as Dr. Roeland mentioned, cannabis and cannabinoids can sometimes decrease the effectiveness of some therapies that a person is on, likely including some cancer treatments, and they can also worsen side effects of other therapies. And then at the same time, cannabis and cannabinoids can be helpful in managing some symptoms of cancer and side effects of cancer treatment. So using them involves a careful weighing of risks and benefits.

So for these reasons, oncology teams really do want to be part of the conversation as someone thinks through decisions around cannabis and cannabinoids. The ASCO guidelines encourage clinicians to be open and non-judgmental and welcome transparent discussions with patients about cannabis and cannabinoids. From there, clinicians should either assist personally if they feel qualified to do so, or refer a patient to high-quality information or an advisor with greater expertise.

As for the types of information that might be helpful to share with the clinical team, a person with cancer who consumes cannabis or cannabinoids might wish to share why they're turning to cannabis, where they get their products, the active ingredients in them—so is it mainly THC or is it mainly CBD­—how they consume them, are they smoking, are they vaporizing, are they taking them by mouth, how often they consume them, what do they experience as the benefits and risks of using cannabis and cannabinoid products? Their clinicians may wish to know whether or not the cannabis products are being used as an add-on to standard treatments or whether they're being used in the place of standard treatments. And as Dr. Roeland suggested, they probably will want to know how much this practice is costing the patient each month and whether it is affordable.

I think it's especially important to speak with your clinical team if you are considering using high-potency cannabis paste in an attempt to treat cancer itself. So not just manage symptoms, but actually treat cancer itself. The reason I think it's so important to share with your cancer team is that these cannabis pastes tend to have very, very high concentrations of THC and sometimes even CBD. And I think your cancer team can be helpful in thinking through the risks and benefits of that, helping to monitor side effects that might arise.

It is commonly the case that people feel a little bit of confusion with very high doses of oral THC.

Dr. Eric Roeland: I absolutely agree. And I think these high doses of cannabis products, they're often a tincture and delivered in a syringe. And it might look like black tar. And people are told to start off with the dosing of a grain of rice. But then they're told that the dose to treat their underlying cancer can be higher than a gram of cannabis a day. In some places it's a gram and a half. This is very high dosing, and it's going to cause people to feel extremely fatigued and increase the risk of falls and being sent to the emergency department. So I want to warn people about this practice in particular, because it can cause harm. We have no evidence that it actually works.

Greg Guthrie: Thanks for that information there. I was wondering, is there a certain person on the health care team that patients should consider talking to, or anyone?

Dr. Ilana Braun: I think anyone. Health care teams keep in close contact with each other. And so this kind of information would be shared amongst the team. So lots of cancer patients begin by sharing with their infusion nurse or their nurse practitioner. They don't even need to share necessarily with their oncologist as a first step. And anyone on the team should, after these guidelines, be able to access high-quality information through their institutions.

Dr. Eric Roeland: And for those patients who might be in a location where they don't have access to an expert or don't have access to educational resources, I think one of the strengths of this current guideline is that we include an appendix, which clinicians can actually use as a 1-page handout for patients and caregivers to answer some of these most basic questions.

For example, I think there's a lot of misunderstanding about how to take cannabis or cannabinoids. And what we do see is there's a big difference between ingesting orally an edible versus smoking or inhaling cannabis. And so, for example, cannabis when eaten by mouth can take up to 2 hours to have its peak effect. And unfortunately, what happens is that patients won't feel anything after several minutes to a half hour and then stack doses to the point that they get a much higher dose than they really need. And so we really encourage people to be aware of, if it's an edible, that it can take up to 2 hours. Whereas with your breathing it in or vaping, the effects can happen almost right away.

But again, it's important to recognize that cannabis, whether it's smoked, vaped, or ingested, can be in your body for up to 12 hours and may even impact your ability to drive. So it's important that if you are going to use these tools in combination with the rest of your medicines, it's important to do it in a safe way.

Another product that is now available, even over the counter at many grocery stores, is cannabidiol, or CBD. CBD in its pure form doesn't have the euphoria associated with products that contain more THC. Most people are using this as an anti-inflammatory, or targeting sleep.

I would like to recognize that in our review of the literature, we discovered that high doses, meaning more than 300 milligrams of cannabidiol a day, actually changed the measurable enzyme levels of the liver. These enzyme levels in the liver are the same levels that we use to determine whether or not you can get your chemotherapy. So you want to make sure that you're not taking excessive doses of cannabidiol, meaning more than 300 milligrams a day, because you don't want your chemotherapy delayed because your liver enzymes might be elevated falsely from the use of high doses of cannabidiol.

Greg Guthrie: That's great, Dr. Roeland. Thanks for adding that. As an additive or part of the cancer care plan, like with all medications, we need to be aware of what we're taking and report to our health care team so we can watch for interactions and potential side effects, right?

So what are the rest of ASCO's guideline recommendations when it comes to this guideline for cannabis and cannabinoids?

Dr. Ilana Braun: So as a committee, we submitted cannabis and cannabinoids to the same level of rigorous scrutiny that we would any other aspect of oncologic care.

I can think of few other ways to validate this area of oncology science than to do so. And after an in-depth evaluation, the ASCO committee concluded that of all the reasons that a cancer patient might medicate with cannabis, the best scientific evidence supports using cannabis or cannabinoids to help with nausea and vomiting caused by cancer drugs when standard medications for nausea and vomiting don’t work well enough.

Of note, ASCO guidelines make clear that there isn't evidence to hang our hats on that cannabis and cannabinoids can treat cancer itself. What's more, early evidence suggests that cannabis and cannabinoids may actually worsen outcomes for people taking a cancer treatment called “immunotherapy.” Gold-standard clinical trials are necessary to confirm these worrisome findings, but for the time being, people on immunotherapy should probably best avoid cannabis and cannabinoids. I think Dr. Roeland and I and the rest of the committee have hope that more scientifically proven indications will emerge as cannabis research progresses.

Dr. Eric Roeland: Dr. Braun has also pointed out to me that there's literature and evidence supporting the use of cannabis and/or cannabinoids for the management of chronic pain not related to cancer. And this has been actually described in other guidelines, and we need to recognize that our patients living with cancer often have chronic pain that may even predate their cancer experience. However, we do not have strong evidence to support that the use of cannabis and/or cannabinoids helps with cancer pain, which is a common reason that people are reaching for these medicines.

Greg Guthrie: Great, thank you, Dr. Roeland. Thank you, Dr. Braun. So this guideline also recommends the use of cannabis or cannabinoids mainly within the setting of a clinical trial, and why is that?

Dr. Eric Roeland: Well, Greg, I think it's incredibly important for people living with cancer and their loved ones to recognize that access to cannabis has far outpaced our ability to validate and study the best methods of using cannabis and cannabinoids in people living with cancer. Meaning access has far outpaced the science that supports its use. We also recognize that just because something is quote, “natural,” doesn't necessarily mean it is also safe, especially in combination with many of the drugs and cancer therapies that patients must receive while they're on treatment.

Therefore, for those of you very frustrated by the lack of evidence to support the use of these medicines in people living with cancer, you should be the first in line to volunteer for any studies that help us collect prospective evidence to demonstrate not only safety but efficacy.

I would also like to recognize how challenging it can be to perform these types of clinical trials based off of the formal designation by the federal government classifying this—cannabis and/or cannabinoids—as a Schedule 1 medicine, which creates multiple barriers for those clinical researchers who want to fully describe the safety and efficacy of these drugs. Therefore, if there is someone near you who is doing clinical research in this space, we greatly would appreciate your involvement in those clinical trials.

Dr. Ilana Braun: I agree with Eric. By participating in clinical trials, a person is doing a very kind thing for others, helping to advance the science behind cannabis and cannabinoids. Only through this controlled, systematic testing will the medical community understand whether cannabis and cannabinoids can be helpful for indications beyond the chemotherapy-related nausea and vomiting.

And we as a society need to understand whether cannabis or cannabinoids can be helpful for cancer pain, for cancer-related poor appetite, to name just a few. These clinical trials will help us move the field forward. And in terms of personal benefit, I could imagine that clinical trials might offer someone more quality-assured cannabis products, more scientifically based dosing guidelines, careful clinical observation should side effects present, and potentially efficacy. But of course there are no guarantees. That's why we're doing the trial.

Greg Guthrie: Thanks, Dr. Braun. Yeah, clinical trials are a safe way to grow our knowledge in cancer care and treatment. And definitely, as Dr. Roeland said, if we don't have evidence, the evidence in this current guideline to support recommendations, then the only way we can truly find that is by participating in clinical trials. And so I would just note that if you're interested in participating in a clinical trial, talk to a member of your health care team. And there are a number of online resources, such as ClinicalTrials.gov, where people can look for research. That's how we advance the science. So is there anything else people with cancer should know about using cannabis or cannabinoids during cancer treatment?

Dr. Eric Roeland: One key message I think for our listeners is to recognize that people have varying tolerances to this class of medicines. And what I frequently observe is that an older patient is offered an edible by their well-intentioned children who want their mom or dad to start eating more in the setting of their cancer. Unfortunately, I've experienced taking care of people that have had side effects associated with the use of cannabis or cannabinoids leading to even emergency department visits and hospitalizations.

And although these products are overall very safe and you cannot quote “overdose” on them or stop breathing because you're taking too much cannabis, it can be very uncomfortable to feel very confused and unable to stand or walk. That can be prolonged for many people, especially those who feel especially weak during their cancer therapy.

And our loved ones mean well, but sometimes the advice that they're providing could actually cause harm. And sadly, I've had many children of patients who have felt incredibly awful after their loved one had a side effect from these medicines, which actually delayed their cancer care.

Greg Guthrie: Excellent point, Dr. Roeland, thank you for that. Dr. Braun, any final notes?

Dr. Ilana Braun: Yeah, so following on Dr. Roeland's thoughts, I would also add that it's important to think about safe storage for such products, particularly if there are children or pets in the home. Cannabis products sometimes look like medicine and sometimes look like candy or baked goods. And so it's important to store them out of the reach of minors and pets.

And the last thing I'll emphasize is this: if you are living with cancer and medicating or thinking of medicating with cannabis or cannabinoids, please consider sharing this information with your clinicians so that they can help you strategize about an optimal course.

Dr. Eric Roeland: I would like to take a moment to thank the American Society of Clinical Oncology for recognizing that we need to address this important need for people living with cancer. And rather than ignore something that's happening every day in the clinic, ASCO chose to convene a panel of experts and coalesce the data and try to figure out what best practices are in this space.

And to that, I am very proud to be a member of ASCO who chooses to lean into these difficult topics rather than run away. I would also say this is a keen opportunity for everyone to advocate for more research in this space. Because talented folks like Dr. Braun, who want to do research in this space, need advocates, need participants, and need funding to fund this type of research. So again, kudos to ASCO, the members of the panel, and, of course, our patients.

Dr. Ilana Braun: Thank you, Eric, for saying that. I am so grateful to have been a part of this really cutting-edge process. And I think that clinical guidelines will help to de-stigmatize cannabis care in a meaningful way in the oncology clinic.

Greg Guthrie: This has been great. Thanks, Dr. Braun. Thanks, Dr. Roeland. If I can interject, I think one of my biggest takeaways here is every patient, caregiver, if they are or are considering cannabis or cannabinoids, the biggest question is to ask, why am I choosing this? And then to find a member of their health care team and talk to them about that. And that's how we protect each other's health and we ensure the best results possible for everyone. So I want to thank you both so much for this engaging discussion. Dr. Braun, Dr. Roeland, thanks for joining us today. And our listeners, if you'd like to learn more about this guideline, please visit www.asco.org/guidelines. Thanks so much for joining us today, and be well.

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