Real-world evidence from 12,112 patients in the TriNetX database indicates GLP-1 receptor agonists reduce metastatic progression by 38-50% in lung, breast, colorectal, and liver cancers compared with DPP-4 inhibitors. This observational cohort, drawn from stage I-III diagnoses, is not an RCT and therefore cannot establish causality; selection bias and unmeasured confounders remain plausible. High GLP-1R tumor expression correlated with 33% lower mortality risk overall and 45% in breast cancer, aligning with The Cancer Genome Atlas analyses. Earlier randomized trials of semaglutide (STEP program, n>17,000) and liraglutide (SCALE, n>5,000) reported no excess cancer signals yet lacked oncology endpoints. The present data extend those safety observations into potential benefit, an angle under-covered outside specialized oncology meetings. Mechanistic hypotheses include direct growth suppression, immune modulation, and reduced inflammation, though inflammation markers were not reported here. Cleveland Clinic investigators disclosed no industry conflicts for this analysis, but broader GLP-1 research frequently receives manufacturer funding. Future RCTs will be essential before any oncologic indication is considered.