GLP-1 Receptor Agonists vs Bariatric Surgery in Breast Cancer: A Comparative Study of Oncologic Outcomes.
This retrospective, real-world study used the TriNetX federated database to compare oncologic outcomes in postmenopausal women aged ≥50 with obesity (BMI ≥30) and stage 0–III breast cancer, across three groups: GLP-1 receptor agonist (GLP-1RA) users, bariatric surgery patients, and those receiving both interventions. Two propensity score–matched analyses (1:1) adjusted for age, BMI, tumor stage, receptor status, adjuvant therapy, and comorbidities. Study 1 (n=3,438 matched per group) found that GLP-1RA users had a lower instantaneous mortality risk (HR 0.57, 95% CI 0.45–0.73) and lower locoregional recurrence (LRR) rate (1.8% vs. 4.7%; HR 0.52) compared to bariatric surgery alone, despite similar 10-year overall survival (87% vs. 83%). Study 2 (n=1,129 matched per group) found that combined bariatric surgery plus GLP-1RA therapy was associated with higher 10-year overall survival (91% vs. 80%; HR 0.44) and lower LRR (2.5% vs. 5.8%; HR 0.52) versus surgery alone. The authors hypothesize potential anti-inflammatory, insulin-modulating, or other metabolic mechanisms beyond weight loss. Key limitations include the observational design, potential residual confounding, lack of GLP-1RA dose/duration data, and inability to establish causality.
Why this grade: While conducted in humans with propensity score matching, the retrospective observational design using a real-world database precludes causal inference and is subject to unmeasured confounding, yielding only limited-grade human evidence.
Obesity contributes to chronic inflammation and estrogen dysregulation, mechanisms linked to increased breast cancer (BC) risk and recurrence, particularly in postmenopausal women. Bariatric surgery and glucagon-like peptide-1 receptor agonists (GLP-1RAs) are effective weight-loss interventions, but their comparative impact on BC outcomes remains unclear. This study compared long-term overall survival (OS) and locoregional recurrence (LRR) among postmenopausal obese BC patients treated with GLP-1RAs, bariatric surgery, or both. Using the TriNetX Network, a real-world federated research database of de-identified electronic records from multiple healthcare organizations, we identified women aged ≥50 years with BMI ≥30 kg/m² and stage 0-III BC. Study 1 compared patients who initiated GLP-1RA therapy ≥6 months after BC diagnosis with those who underwent bariatric surgery during the same interval. Study 2 compared patients who received both bariatric surgery and GLP-1RA therapy with those who underwent surgery alone. Propensity score matching (1:1) was performed for age, BMI, tumor stage, receptor status, adjuvant therapy, other cancers, and comorbidities. Outcomes included OS and LRR, assessed from 30 days to 10 years after the index event (bariatric surgery or GLP-1RA initiation). Hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated using Cox proportional hazards models. In Study 1, 22,532 GLP-1RA users and 3,468 bariatric surgery patients were identified; 3,438 were matched in each cohort. 10-year OS was similar (87% vs. 83%), yet GLP-1RA users experienced significantly lower instantaneous mortality risk (HR 0.57, 95% CI 0.45-0.73), indicating fewer or delayed deaths over time. LRR occurred in 1.8% vs. 4.7% (HR 0.52, 95% CI 0.39-0.70), also favoring GLP-1RA therapy.In Study 2, 1,220 patients underwent both bariatric surgery and GLP-1RA therapy and 3,468 underwent surgery alone; 1,129 were matched per group. The combination group showed higher OS (91% vs. 80%; HR 0.44, 95% CI 0.29-0.67) and lower LRR (2.5% vs. 5.8%; HR 0.52, 95% CI 0.33-0.81). Among postmenopausal women with obesity and stage 0-III BC, GLP-1RA therapy was associated with improved OS and lower LRR compared to bariatric surgery alone. Combination therapy achieved the most favorable oncologic outcomes, suggesting a potential synergistic effect. The advantage observed with GLP-1RAs may reflect oncologic effects beyond weight loss, potentially through anti-inflammatory, insulin-modulating, or other metabolic pathways. These findings support further investigation into the underlying biologic mechanisms and potential role of GLP-1RAs in oncology.
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