Obesity and weight gain are associated with adverse outcomes following breast cancer diagnosis; some breast cancer treatments contribute to postdiagnosis weight gain. We evaluated patients with breast cancer who were prescribed a glucagon-like peptide-1 receptor agonist (GLP-1 RA), with follow-up weight data available. Weights were categorized by time from GLP-1 RA initiation; a linear mixed effects model with a random intercept for baseline weight was used to assess mean weight change at each time point. Among 75 patients, the median age was 52 years (range, 27-74), 62 (86%) were postmenopausal, and 59 (79%) had diabetes. Additionally, 68 (91%) patients had stage 0 to III breast cancer, and 62 (84%) had estrogen receptor–positive disease. The median body mass index (BMI) at baseline was 34 (range, 23-50). The mean weight change was –2.9 kg (95% CI, –4.1 to –1.7) at 6 months and –4.2 kg (95% CI, –5.5 to –2.9) at 12 months; mean weight change at 12 months was –5% (95% CI, –6% to –3%). In univariable and multivariable analyses, age, baseline BMI, diabetes, stage, histology, receptor status, menopausal status, and concurrent endocrine therapy use were not significantly associated with 5% or greater weight loss at 12 months. These results support the development of clinical trials to optimize the use and dosing of GLP-1 RAs for weight loss in patients with breast cancer.
A 2025 study studied this question.