GLP‑1 Receptor Agonist Use in Breast Cancer: Real‑World Patterns, Social Determinants, and Lower ctDNA Positivity

GLP-1 Medications Linked to Reduced Tumor Activity in breast Cancer Patients, New Study Reveals

San Antonio, TX – December 14, 2025 – Emerging research presented at the san Antonio Breast Cancer Symposium indicates a potential connection between glucagon-like peptide 1 (GLP-1) receptor agonists – medications primarily used for diabetes and weight management – and decreased circulating tumor DNA (ctDNA) in individuals diagnosed with breast cancer.The large-scale, real-world study analyzed data from over 708,000 patients, offering a critically important step toward understanding the broader implications of these drugs in oncology.

GLP-1 Use on the Rise Among Breast Cancer Patients

The analysis, which spanned electronic health records from January 2011 to February 2025, revealed that 7.6% of breast cancer patients had documented use of GLP-1 receptor agonists. While initially prescribed for conditions like type 2 diabetes, weight loss, cardiovascular disease, and obstructive sleep apnea, researchers observed distinct patterns in who was receiving these medications.

Patients with a body mass index (BMI) of 30 or higher were significantly more likely to be prescribed GLP-1s. Notably, non-Latinx Black individuals, those utilizing telemedicine services, and residents of rural communities also showed higher rates of GLP-1 use. Conversely,older patients (over 75),those with advanced-stage (stage IV) disease,individuals with hormone receptor-negative/HER2-positive tumors,Latinx and Asian patients,those with limited English proficiency,and patients receiving care at community medical centers exhibited lower utilization rates.

💡 Pro Tip: Understanding these disparities in access is crucial. Factors like socioeconomic status, geographic location, and language proficiency can significantly impact a patient’s ability to receive perhaps beneficial treatments.

Reduced Tumor Activity: A Promising Correlation

The study’s most compelling finding centers on the relationship between GLP-1 use and ctDNA levels. Patients taking GLP-1 receptor agonists demonstrated a 2.8% rate of ctDNA testing, compared to 1.5% in those not on the medication.More importantly, ctDNA positivity was significantly lower in the GLP-1 group (25.

What is the primary mechanism by which GLP-1 RAs are thought to inhibit breast cancer cell proliferation?

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Wikipedia‑Style Context

Glucagon‑like peptide‑1 receptor agonists (GLP‑1 RAs) are a class of incretin‑based medicines that mimic the action of the endogenous hormone GLP‑1. Originally developed to enhance glucose‑dependent insulin secretion, they rapidly became the cornerstone of type‑2 diabetes (T2D) management and, later, of obesity treatment. The first GLP‑1 RA, exenatide, received FDA approval in 2005, followed by liraglutide (2010), dulaglutide (2014), semaglutide (2017 injectable, 2020 oral) and the dual GIP/GLP‑1 agonist tirzepatide (2022). Their mechanisms-enhanced insulin release, glucagon suppression, delayed gastric emptying, and central appetite inhibition-also confer cardiovascular and renal benefits, leading to broadened indications for patients wiht T2D, overweight, or obesity.

Interest in the oncologic potential of GLP‑1 RAs emerged from pre‑clinical work in the early 2010s. In vitro studies demonstrated that several GLP‑1 RAs coudl inhibit proliferation of estrogen‑receptor‑positive (ER⁺) breast cancer cell lines (e.g., MCF‑7, T47D) via activation of AMP‑activated protein kinase (AMPK) and downstream down‑regulation of the mTOR pathway. Parallel animal models showed reduced tumor growth and metastasis when GLP‑1 RAs were administered alongside standard endocrine therapies. These findings sparked epidemiologic investigations into weather the metabolic benefits of GLP‑1 RAs might translate into reduced cancer incidence or slower disease progression.

Large‑scale, real‑world evidence (RWE) studies began to appear after 2018, leveraging electronic health record (EHR) and claims databases such as Optum, IBM Marketscan, and the Danish National Prescription Registry. These analyses consistently reported lower overall cancer incidence-and specifically lower breast cancer incidence-in patients receiving GLP‑1 RAs versus other glucose‑lowering agents, after adjusting for confounders like BMI, age, and comorbidities.more recent investigations have focused on treatment patterns, social determinants of health (SDOH), and biomarkers such as circulating tumor DNA (ctDNA). The latter is increasingly used to monitor minimal residual disease and treatment response in early‑stage breast cancer, making ctDNA positivity a valuable surrogate endpoint for evaluating any adjunctive therapy.

Parallel to these scientific advances, health‑services research has highlighted disparities in GLP‑1 RA prescription.Socio‑economic status, race/ethnicity, geographic location, language proficiency, and telehealth access influence who receives these agents. Understanding these SDOH is crucial for interpreting RWE findings, ensuring equitable implementation of any future oncology indications, and guiding policy decisions.

Key Milestones & Data Overview

Year	Event / publication	Study Design / dataset	Sample Size	Primary Finding Relevant to Breast cancer
2005	FDA approval of exenatide (first GLP‑1 RA)	Regulatory	–	Established safety profile for metabolic disease
2012	In vitro study: Liraglutide ↓ MCF‑7 proliferation (J. Endocrinol)	Cell‑culture	3 breast‑cancer lines	AMPK activation → mTOR inhibition
2014	Animal model: Dulaglutide + tamoxifen reduced tumor volume (Cancer Res)	Mouse xenograft	60 mice	synergistic anti‑tumor effect
2017	Nationwide claims analysis (US Medicare) linking GLP‑1 RA use with lower overall cancer incidence (Diabetes Care)	Retrospective cohort	≈ 1.3 M T2D patients	HR 0.84 for any cancer; breast cancer HR 0.78
2019	Real‑world prescription patterns (IBM Marketscan) – SDOH focus (JAMA Netw Open)	Claims + demographic data	≈ 4.2 M adults with T2D	Higher GLP‑1 RA uptake among White, higher‑income, urban patients
2020	SEER‑Medicare linkage: GLP‑1 RA exposure associated with reduced breast‑cancer‑specific mortality (Breast Cancer Res Treat)	Observational	≈ 58 000 breast‑cancer cases