GLP-1 Therapies May Shape Future Breast Cancer Survivorship and Metabolic Care Strategies

In this Q&A with Pharmacy Times, Bernard Fuemmeler, PhD, MPH, professor and Gordon D. Ginder, MD Chair in Cancer Research at Virginia Commonwealth University (VCU) School of Medicine, and Kristina Tatum, PsyD, MS, Instructor at VCU School of Public Health, discuss the potential role of glucagon-like peptide-1 (GLP-1) receptor agonists in breast cancer outcomes and survivorship care. The experts review observational findings suggesting associations between GLP-1 therapies and improved survival and lower recurrence risk in patients with obesity and type 2 diabetes. They emphasize that although the findings are promising, additional research is needed to better understand the biological mechanisms, optimal patient populations, timing of therapy, and long-term safety considerations.

Pharmacy Times: Your study found that GLP-1 receptor agonist use was associated with improved survival and lower recurrence risk among patients with breast cancer. What do you believe may be driving these outcomes biologically — is it primarily weight loss and metabolic improvement, or do you think GLP-1 therapies could have more direct effects on tumor biology?

Bernard Fuemmeler, PhD, MPH: I can start off by saying that this study was not really designed to test some of the biological implications directly, but we are excited about future studies that can help tease apart some of the drivers behind what we are seeing in our data. I think the evidence is leaning toward the possibility that these findings may be more related to controlling metabolic conditions, cardiovascular conditions, and obesity-related factors that can affect tumor biology. It may be that these medications are impacting those comorbidities, but we are still…trying to fully understand these mechanisms. There have been some animal model studies attempting to tease this apart, but we have not yet fully explored these mechanisms within human populations.

Kristina Tatum, PsyD, MS: It is likely that the associations we observed in our study are multifactorial. Moving forward, an important next step will be to directly evaluate potential anticancer effects and weight changes as possible mechanisms, as Dr Fuemmeler mentioned, while also identifying which patients may be most likely to benefit from GLP-1 therapies to better inform future clinical guidance.

Pharmacy Times: Given the growing use of GLP-1 therapies like semaglutide and tirzepatide, what should oncology clinicians and pharmacists take away from these findings right now when managing patients with breast cancer and obesity or type 2 diabetes?

Tatum: Our study included newer GLP-1 receptor agonists, such as semaglutide and tirzepatide, but we did not examine how many patients were using these newer agents compared with older GLP-1 medications included in our study that are less commonly prescribed today. With that said, our results are consistent with [those of] prior observational studies examining GLP-1 therapies and cancer survival outcomes, further supporting the possibility that GLP-1 therapies may have a role in breast cancer care for some patients. However, it is still important at this time to consider factors such as safety, dosing, timing, and individual patient characteristics, which need to be better understood, particularly given the widespread use of GLP-1 therapies for weight management and type 2 diabetes management.

Fuemmeler: I would just add that conditions such as obesity and type 2 diabetes need to be managed carefully in patients with cancer because they can create complications during survivorship. Clinicians, pharmacists, oncologists, and primary care providers now have new methodologies and tools, such as these weight loss medications, that may help manage these conditions. I think informed conversations between clinicians and patients are very important, particularly shared decision-making around how to use these medications, while carefully considering both the benefits and potential adverse effects. Using these therapies to help manage these more problematic conditions is likely…called for at this point.

Pharmacy Times: The study analyzed electronic health records from more than 840,000 patients over a long follow-up period. What aspects of the data surprised you most, particularly regarding recurrence reduction or long-term survival outcomes?

Fuemmeler: I think we were surprised to see associations showing that GLP-1 medications were linked to better survival outcomes and a lower chance of recurrence over this 10-year observation period. These findings were observed in women with obesity as well as women with diabetes, and the effects were robust and significant.

At the same time, we want to temper these findings with some caution and remain cautiously optimistic because this was an observational study, not a randomized trial. Because of that, we cannot determine causation, and we also cannot fully determine the effects of some of the newer medications. There is still a great deal of work to be done in this area.

What these findings do is open the door to a better understanding of these associations. We believe the findings are important, but we also want them to be replicated. We need follow-up studies to better tease apart the underlying mechanisms and to use different databases that can provide additional supporting evidence for these findings.

Pharmacy Times: There has been increasing discussion around integrating weight management into cancer survivorship care. How could these findings potentially change conversations between oncology teams, pharmacists, and patients regarding supportive care and long-term survivorship strategies?

Tatum: We can’t establish causation from this observational study, as we mentioned before, but we do believe the findings provide clinically relevant insight for patients with breast cancer, particularly those with comorbid conditions such as obesity or type 2 diabetes. We know that metabolic health plays an important role in cancer outcomes, and certain breast cancer treatments, such as endocrine therapy, can also impact metabolic functioning.

Taken together, this is a timely study that supports the idea that weight management should be considered as part of survivorship care. What that ultimately looks like is still to be determined, but it raises consideration for the potential role of GLP-1 receptor agonists alongside other approaches, such as behavioral interventions and, in some cases, bariatric surgery.

Overall, I believe these findings highlight the importance of addressing metabolic health as part of a long-term survivorship strategy.

Pharmacy Times: Since this was an observational retrospective study, what are the most important next steps needed before GLP-1 receptor agonists could be more formally considered within oncology treatment or survivorship guidelines?

Fuemmeler: I think GLP-1 agonists can currently be useful for patients with diabetes and obesity, particularly when used under the care of a physician and a care team that is closely monitoring changes in weight and overall health.

I think the next steps are really to determine for whom these medications are most helpful and at what point during treatment they may play the greatest role. Going back to the beginning of our discussion, an important question is whether some of these medications could also be useful for individuals who do not have high levels of obesity or type 2 diabetes. For example, could they be beneficial for women who are overweight but not yet obese? That is a question that could be answered through carefully designed clinical trials.

Ultimately, we need to better understand which patients benefit the most, when these medications should be incorporated into treatment or survivorship care, and whether there are strategies that may be useful for women with varying comorbid conditions.

Tatum: I’ll just say that our findings, at this time, may help inform…more of a thoughtful conversation about metabolic health and breast cancer survivorship care between patients and providers.

Read the full article on their study here.