GLP-1 Receptor Agonists in Cancer Care: Oncology Pharmacists Weigh Benefits, Risks, and Real-World Complexities

As glucagon-like peptide-1 (GLP-1) receptor agonists move beyond diabetes and obesity into mainstream conversations in oncology, pharmacists are navigating a rapidly evolving evidence base and complex clinical scenarios. In this conversation at the Hematology/Oncology Pharmacy Association 2026 Annual Conference, Colleen McCabe, PharmD, BCOP, and Lindsay Mundy, PharmD, describe how GLP-1 therapies first entered their oncology practices, the challenges of overlapping toxicities during chemotherapy, and why shared decision-making is essential when data remain unsettled. Their insights highlight both the promise and the uncertainty surrounding GLP-1 agents in cancer care—and the practical considerations oncology pharmacists must weigh every day.

Q: GLP-1 receptor agonists were designed for diabetes and obesity, but now they’re showing up in oncology conversations. How did you first start encountering GLP-1 RAs in your clinical practice, and what prompted you to dig deeper into the evidence?

Colleen McCabe, PharmD, BCOP: So this is actually how this topic came to light. We were kind of having a clinical debate back and forth about when to hold glucagon-like peptide-1 (GLP-1) receptor agonists in patients undergoing cancer treatments. For instance, for me, I do head and neck cancer. For concurrent chemoradiation patients, weight loss is already a huge issue, which can really delay healing times. I often will hold the GLP-1 receptor agonists during their treatment to not have to deal with the weight loss implications. That kind of started a conversation about how that impacts different disease states.

Lindsay Mundy, PharmD: Yeah, yeah. It was an interesting conversation because ours is a lot more nuanced. I work with sarcoma and was previously in melanoma, and it's a lot more nuanced in the conversation. It's a lot more shared decision-making and having a thoughtful conversation with the patient. It's not an immediate no. That's why I was asking Lindsay, “Are there other considerations that you have?” I have this kind of more gray-area case and want to talk through it with her. It's really interesting that it's just an absolute no for treatment. We thought that this talk and going through some of the data and what we think about would be really helpful for other oncology pharmacists.

Q: The session describes associations that can go in multiple directions—risk reduction in some cancers, risk increase in others, and neutral findings elsewhere. How do you counsel a patient or a colleague when the data are genuinely unsettled? What does shared decision-making look like in that kind of uncertainty?

Mundy: Yeah, so I think that was something, when we started to look into this data, that we thought would make a great presentation for clinical oncology pharmacists, because there is this primary data that's starting to trickle out. A lot of it's retrospective reviews, but that's what we have right now. That's where we structured this to look at those benefits and risks for patients that are not oncology patients—so what it looks like from either prevention or if we're seeing cancer signals in those patients—versus the patients undergoing cancer treatment. Are there any benefits and then risks, which again led back to our question of overlapping side effects: nausea, vomiting, weight loss, nutritional deficiencies. That's again how we tied in how we do that shared decision-making.

McCabe: Yeah, definitely. We're hoping that this talk will walk through, step by step, example cases of how to use the framework of shared decision-making to help pharmacists have a tool to be able to have those discussions with patients. When you're sitting in the clinic room, you have a new patient starting chemotherapy or a different agent and notice that there is a GLP-1 receptor agonist on their medication list. What's that next step? How are you engaging with the provider? But also, how will you have that conversation with the patient, and what are all the things you're considering?

We outline in our presentation exactly how to start doing that—how to walk into the room and start that conversation with the patient, making sure that it's really including their thought process behind their GLP-1 receptor agonist. Sometimes it's for diabetes, of course, and sometimes it's also for weight loss. Someone who has had a huge weight loss journey or someone who just started because they were interested in, as it's advertised, slimming down for summer, or something that’s not as medically driven. Being able to open those conversations in a curious way lets you find all the factors you need to consider for helping make a decision with the team.

Q: Overlapping toxicities like nausea, vomiting, and delayed gastric emptying are a real concern when GLP-1 RAs are layered on top of cancer treatment. Can you walk us through a case where managing that overlap was particularly challenging and what you learned from it?

McCabe: Yes. One of the cases that I run into commonly is that we give a lot of highly emetogenic chemotherapy, so we already baseline struggle with patients’ nausea and gastrointestinal (GI) side effects, which of course can be what we see on the GLP-1 receptor agonist agents as well. Patients already come in with some baseline queasiness, potentially, or if we start them on chemotherapy and they start to have side effects during their first cycle, it's really hard to tease out: Is this because they're on a GLP-1 receptor agonist and these side effects are worsening now, or is this only chemotherapy?

Those have been the hardest to deal with. The practice that I use personally is we ask patients to hold for at least a cycle just so we can get an idea of their true side effects from the therapy itself. Then, if the patients are interested in cycle two or three and they really want to add it back on, at least we have an idea: Okay, now that they're adding it, these other side effects are from the agent. And let's have another conversation.

I will say most times patients, after they've gone through a cycle or two of chemotherapy, don't feel as interested or concerned about resuming the GLP-1 receptor agonist, just because they can feel for themselves the true side effects that come with chemotherapy.

Mundy: And I think especially with the side effects that are listed, they're generally multifactorial anyway. When we're talking about nausea, vomiting, weight loss, fatigue, we're also looking at cancer cachexia and anorexia and maybe weight loss just from undergoing these therapies. I think it's difficult to completely tease those out. Often, if we have an opportunity to remove something for the timeframe they're undergoing chemotherapy, to make that chemo a little easier for the patient—and also being able to share that's why we want to do that—I think they're much more willing and understand where we're coming from as practitioners.

Q: Sarcoma and melanoma are relatively rare malignancies, which means GLP-1 RA data in those populations is likely sparse or extrapolated from broader cohorts. How do you approach evidence gaps specific to your patient population, and are there any mechanistic signals worth watching?

McCabe: Yeah, that's a great question, and that's something I think in my practice, being in rare diseases, that I struggle with across the board, of course, for other things, not even just including GLP-1 receptor agonists and how we handle those for our patients. I handle it the same as I handle clinical discussions that don't have a lot of data behind them.

Any sort of general guidance from, you know, the American Society of Clinical Oncology (ASCO) or the National Comprehensive Cancer Network (NCCN) or expert panels is what I go to first, and I'm hoping that in the next couple of years we could have some guidance from one of those organizations, or something similar, to have a stance on how to handle these. They get together experts of the field, and through thoughtful discussions, are able to develop guidance. I hope we do have more guidance like that in the future.

But before that, we really extrapolate on what we've seen in our practice, and we share it with the patient. I've had many, many patients in sarcoma who have been on GLP-1 receptor agonists and have not stopped it, or have stopped it. Usually, I share with the patients other patients’ experiences and what they’ve had. I don't use the lack of data and these incidental cases to make global decisions across patients, but I use what I've seen in clinic. I try to have conversations with as many other experts as I can so that we can continue to provide the best care for our patients, because it changes daily, of course.