GLP-1 Use Appears Safe During Certain Cancer Treatments
For oncologists, the rapid rise in use of glucagon-like peptide-1 (GLP-1) receptor agonists has opened an important new area of research extending well beyond metabolic disease.
At the 2026 ASCO Annual Meeting, Dr. Neil M. Iyengar, a breast medical oncologist and director of Cancer Survivorship Services at Emory Winship Cancer Institute, discussed emerging research about safety when using GLP-1s alongside cancer treatments and the drugs’ role in cancer prevention with SurvivorNet Connect.
Can GLP-1s Be Safely Combined With Cancer Therapy?
Dr. Iyengar noted that some of the earliest observational data came from his team’s work at Memorial Sloan Kettering Cancer Center, where researchers evaluated patients receiving GLP-1 receptor agonists alongside chemotherapy or endocrine therapy for breast cancer.
“What we found in a small subpopulation was that the GLP-1 receptor agonists were overall safe when used with either chemotherapy or hormone therapy,” he said.
However, investigators also observed that weight loss appeared to be less pronounced when GLP-1s were combined with endocrine therapy than in the general population, raising questions about potential biologic interactions and the need for prospective trials to identify optimal dosing strategies.
At the same time, Dr. Iyengar cautioned that a small number of early studies have raised important questions about how GLP-1 receptor agonists should be used alongside cancer treatment. He pointed to preliminary data from researchers at UT Southwestern suggesting that, among patients with triple-negative breast cancer receiving chemotherapy and immunotherapy, concurrent treatment with a GLP-1 receptor agonist may reduce the effectiveness of cancer therapy.
While he emphasized that these findings require further validation, he said they highlight the need for prospective studies to determine the safest and most effective way to integrate GLP-1 receptor agonists into cancer care.
“These are potentially very powerful tools in the oncology setting, but we need to study how best to use them,” Dr. Iyengar said. “Not only so that we’re not harming our patients, but also so that we can leverage their incredible weight loss effects to improve outcomes.”
Subsequent data from MD Anderson Cancer Center reproduced similar findings, strengthening interest in this area. Meanwhile, the volume of evidence has expanded dramatically. According to Dr. Iyengar, nearly 90 studies presented at ASCO examined GLP-1 receptor agonists, leveraging large observational datasets involving millions of patients.
Large Studies Point to Benefits Beyond Weight Loss
Collectively, these studies suggest that GLP-1 receptor agonists are associated with a reduced risk of developing many obesity-related cancers and may improve outcomes for some patients already receiving cancer treatment.
“The bottom line is that many obesity-related cancers…are significantly reduced in patients with or without diabetes who take GLP-1 receptor agonists,” Dr. Iyengar explained. He added that several studies have also suggested GLP-1s “seemed to help the cancer therapies work better in fighting the cancer.”
Despite the encouraging findings, Dr. Iyengar emphasized that important questions remain. He highlighted preliminary data from UT Southwestern suggesting that concurrent GLP-1 use during chemotherapy and immunotherapy for triple-negative breast cancer may reduce treatment efficacy in some patients.
While these findings require validation, they underscore the need for carefully designed prospective trials to determine which patients are most likely to benefit, when GLP-1 therapy should be initiated, and how it can be integrated safely with cancer treatment.
