Patients with breast cancer (BC) and comorbid obesity or type 2 diabetes (T2D) often experience poorer long-term outcomes. A retrospective cohort study published in JAMA Network Open evaluated the association between glucagon-like peptide-1 receptor agonist (GLP-1 RA) use and long-term mortality and recurrence-free survival (RFS) in this population.

The study included 841,831 women aged 18 years or older diagnosed with BC between April 2006 and April 2023 across 68 US health care organizations within the TriNetX Collaborative Network. After exclusions and 1:1 propensity score matching, analyses included three cohorts: GLP-1 RA use versus nonuse among patients with obesity (n=1610), GLP-1 RA use versus insulin or metformin among patients with T2D (n=2323), and GLP-1 RA use versus sodium-glucose cotransporter 2 (SGLT2) inhibitors among patients with T2D (n=4052). 

The primary outcome was all-cause mortality, while RFS served as the secondary outcome over a 10-year follow-up period. The overall study population had a mean age of 69.1 years.

Findings

• In the obesity cohort, GLP-1 RA use was associated with lower all-cause mortality (HR 0.35; 95% CI 0.21-0.58; P<.001) and improved RFS (HR 0.44; 95% CI 0.30-0.64; P<.001) compared with nonuse.

• Among patients with T2DM, GLP-1 RA use versus insulin or metformin was associated with lower all-cause mortality (HR 0.09; 95% CI 0.06-0.15; P<.001) and improved RFS (HR 0.33; 95% CI 0.21-0.50; P<.001).

• No significant differences were observed between GLP-1 RA users and patients receiving SGLT2 inhibitors.

• Postmenopausal subgroup and landmark analyses yielded findings consistent with the primary analysis.

The findings suggest a potential association between GLP-1 RA use and more favorable long-term outcomes among patients with BC and metabolic comorbidities. Further evaluation in randomized clinical trials is needed.