Successful Reversal of Tamoxifen-Associated Weight Gain and Metabolic Dysfunction with Liraglutide in a Breast Cancer Survivor: A Case Report.

Introduction: Adjuvant endocrine therapy for breast cancer - particularly tamoxifen - is commonly associated with weight gain, increased adiposity, and metabolic dysfunction. Lifestyle measures often fail to reverse these effects. Evidence regarding glucagon-like peptide-1 (GLP-1) receptor agonists in this specific context remains limited. Reversal of tamoxifen-associated weight gain with liraglutide has been rarely reported. Case Presentation: A 58-year-old postmenopausal woman with stage IIA, hormone-receptor positive breast cancer experienced marked weight gain after 24 months of tamoxifen therapy, despite diet and exercise. She developed prediabetes, insulin resistance (assessed by Homeostatic Model Assessment of Insulin Resistance [HOMA-IR] 4.9), and dyslipidemia. Liraglutide, a glucagon-like peptide-1 (GLP-1) receptor agonist, was initiated and titrated to 3.0 mg/day. Over 12 months, she lost 18.5 kg, and her metabolic parameters, including HOMA-IR and glycated hemoglobin (HbA1c), normalized. Tamoxifen therapy was continued without adverse effects. Conclusion: This case suggests that liraglutide may reverse substantial tamoxifen-associated weight gain and related metabolic derangements in a breast cancer survivor. The observed improvement exceeded what is typically achieved with lifestyle measures alone. Formal studies are needed to define the role of GLP-1 receptor agonists in managing endocrine therapy-related metabolic complications.