Chapters Transcript Video 2026 ASCO Breast Cancer Highlights: BWEL Harold Burstein, MD, PhD, and Jennifer A. Ligibel, MD discuss new research from the Breast Cancer Weight Loss (BWEL) trial, as well as recommendations for lifestyle, diet and GLP1 agonists. I'm Doctor Harold Burstein and welcome to the Breast Cancer Breakthrough series we've been doing with our breast oncology faculty here at Dana-Farber. We've been profiling some of the most important data to come out of the annual ASCO meeting. One of those presentations was an update of the BWEL study, an important study of diet and lifestyle interventions in breast cancer survivors led by our very own Doctor Jennifer Ligebel, who is professor of medicine here at Harvard Medical School and leads our Zacom Center for Integrative Oncology. Jennifer, uh, great to have you with us today. Tell us about this trial, uh, what the takeaways are, and then I wanna have a discussion about where we're at with lifestyle and diet and breast cancer survivorship. Absolutely, thanks so much for having me here today. So I'm going to talk a bit about our BeW trial, looking at the effect of a weight loss intervention on quality of life and symptoms in women with breast cancer. As a bit of background, obesity is a poor prognostic factor in early stage breast cancer. We know that when a woman has obesity and she's diagnosed with breast cancer, she has a higher risk of dying from her breast cancer as compared to a leaner woman. We also know that obesity is linked to reduced physical function, poor quality of life, and an increased risk of side effects from common cancer treatments. There have been a few small studies that have looked at the effect of a weight loss intervention on quality of life, but more information about this effect is needed. So the breast cancer weight loss trial is a phase 3 clinical trial that is testing whether a structured weight loss intervention focused on caloric restriction and increased physical activity will improve invasive disease-free survival in women with stage 2 and 3 HER2 negative breast cancer and a body mass index of at least 27 kg per meter squared. 3180 women were randomized to this trial. Um, they were assigned to a health education program plus a two-year lifestyle-based weight loss program or to health education alone. Last year, we published a study showing that the weight loss intervention was effective. Women who were assigned to the weight loss intervention lost almost 6% of their baseline body weight versus controls at one year. At this year's ASCO annual meeting, we looked at some of our first quality of life outcomes. So, the 1st 542 patients who were randomized to the BWEL study took part in a mandatory health outcomes substudy that was designed to evaluate the effect of the weight loss intervention on physical function and other quality of life metrics. Patients completed the promised 29 version 2.0 measure at baseline 6 in 24 months, and we Looked at the differences between arms at 6 months, which was our primary outcome, and then longitudinally over time. What we found was that there was a highly significant effect of the weight loss intervention on physical function, which was our primary outcome. At 6 months, there was a between group difference of about 2 points on the promised measure, and the statistically significant benefit was maintained through the 2-year duration of the weight loss intervention. We also saw that there were other benefits of the weight loss intervention. There was a statistically significant improvement in global physical health and in global mental health, which are the two primary constructs of quality of life at 6 months. There was also a significant improvement in social roles and activity, looking at how people functioned in their daily lives, and a decrease in fatigue. All of these benefits, other than fatigue, were maintained throughout the 2-year intervention period. So in summary, we found that this telephone-based diet and exercise weight loss program had a significant impact on physical function and other quality of life metrics at 6 months, and that these benefits, especially looking at overall quality of life and physical function, were maintained through the 2-year intervention period. We will continue to follow patients to look at whether these improvements in quality of life translate into better breast cancer outcomes. Fantastic. So, um, uh, first of all, great to see a large study looking at this, uh, both from a quality of life point of view and ultimately a cancer impact point of view, which is gonna be very powerful. These questions arise every day in clinic for breast oncologists. What can I do besides the drugs you're prescribing me, the radiation therapy, the surgery I need? What can I do to improve my quality of life and hopefully even prevent a breast cancer recurrence? So first, what do you say to patients in that situation about some core things that you might have taken away from the BWEL study or other concrete suggestions to improve their quality of life? So I think one of the important things about this study was demonstrating that There were many benefits of the degree of weight loss that we saw with a lifestyle-based weight loss program. We know now that there are a lot of patients that are taking GLP-1s that are experiencing 15-20% loss of baseline body weight. This was a much more modest amount of weight loss, but we saw some really tangible benefits here from these changes in physical activity, caloric restriction. And these were maintained through the two year intervention period too. So really showing that things that patients do themselves can make a big difference in how they feel. And if you were to frame this for a patient, is this 30 minutes a day of exercise? Is this a 2000 calorie daily limit? What are the kind of parameters you would give them? So what we did in our weight loss intervention was we looked at patients' baseline caloric intake. We looked at the amount of weight they wanted to lose, which we modeled for. Each person as an ideal 10% baseline body weight loss, which you really never see with lifestyle-based uh interventions, and we use that to determine whether they, how many calories they would reduce every day. It was generally between 500 and 1000 calorie restrictions, fewer, yes. And then we also paired that with 150 minutes of physical activity a week, 150 a week, so. I can't do 30 minute walk. 30 minutes sounds about right. Um, so you already alluded to GOP-1 agonists. There were several provocative presentations at the meeting suggesting that in a Diagnosed diagnostic population getting screening for breast cancer that perhaps those women on GLP agonists had a lower incidence of breast cancer. There have been some other trials suggesting GLP-1 agonists might even lower the risk of a recurrence of breast cancer. Let me ask you first, is it safe for breast cancer patients to be on these drugs? And then secondly, is there an oncologic indication for them above and beyond the indications for obesity, diabetes management, or other standard indications at this point? So we know that obesity is a risk factor for developing breast cancer in postmenopausal women and for poor outcomes, higher risk of recurrence and mortality for both younger and older women. We know that GLP-1 agonists help people lose a lot of weight, and there are these observational analyses. So that's what we've seen so far with the GLP-1s is these big database analyses where researchers have looked at who has taken these prescriptions, and they've matched them to people who haven't taken them, and this is one of the parts that's very tricky. Because many of the studies have kind of paired people who take GLP-1s to people taking certain diabetes drugs. So you have everybody in the population not taking GLP-1s who has diabetes, whereas the other group is a mix of people taking them for obesity, for diabetes. What's hard here is that we know that that diabetes is also a risk factor for breast cancer, and it's a risk factor for poor outcomes. So I think these are really provocative data with GI. GLP1s really, really interesting, but definitely not definitive at this point because there's some key features about how the populations are matched, why people are taking the GLP-1 versus other drugs. We really need some randomized trials, so there's not an oncologic indication for the drugs yet, but I think there's an enormous amount of potential there. And it sounds like we can tell a patient that so far as we know they're perfectly safe in breast cancer survivors and breast cancer patients. Well, you look like you have a coffee. I said, OK, hold the asterisk. They're, they're reasonably safe, and there's certainly no suggestion they worsen the risk of cancer in any way, correct? I would say that. What was your asterisk there? So the treatment for patients with breast cancer, as you know, has gotten much more complicated, and we use a lot of new targeted therapies, and there's no information about safety in patients that are. Taking GLP1s and CDK46 inhibitors, there's not a lot of information about any drug interactions. We do know that the drugs can cause some overlapping side effects with GI issues, especially, for example, a bemicyclib with the diarrhea patients experience. So I think we don't really know yet about how some of these agents may interact with each other, but. What we're seeing is this huge natural experiment where millions of people are taking these drugs and millions of patients have had breast cancer. So I think we're going to learn a lot more in the next few years. But you make a good point about especially the orally available targeted therapies with GI side effects. You might want to be a little more cautious before plunging in. We've been talking about lifestyle and dietary modifications for breast cancer survivors based on updated data from the ASCO 2026 meeting. One of the world's experts in the space, Dr. Jennifer Lugerbilt, is joining me. Thank you for joining us. We look forward to seeing you soon. Published August 22, 2026 Created by Related Presenters Harold Burstein, MD, PhD Medical Oncology View Full Profile Jennifer Ligibel, MD Medical Oncology View full profile