Metformin in cancer immunotherapy: knowledge mapping of an evolving field through bibliometric analysis (2007-2026)

The convergence of metformin and cancer immunotherapy has recently gained intense global interest, driven by evidence that metformin can remodel the tumor immune microenvironment and potentiate immune-based treatments. No bibliometric study has yet mapped this rapidly expanding field. We searched the Web of Science Core Collection from January 1, 2007, to July 8, 2026, for English papers containing metformin and immunotherapy terms, retrieving 328 papers. VOSviewer 1.6.19 and CiteSpace 6.2.R4 were used to quantify publications, citations, collaboration networks (countries, institutions, and authors), keyword co-occurrence, citation bursts, and temporal trends. The compound annual growth rate (CAGR) was 26.71% per year; 93.3% of papers were published after 2018. In the mapped country network, China contributed the most publications (n = 167), whereas the United States had the highest citation count (4402) and total link strength (56). Sun Yat-sen University led institutional output (n = 12), and Heiichiro Udono was the most productive mapped author (n = 8). The Journal for ImmunoTherapy of Cancer was the leading publication source (n = 12). Research on metformin plus immunotherapy is surging. Future priorities include elucidating the impact of metformin on immunotherapeutic efficacy across tumor types, optimizing combination regimens, and identifying predictive biomarkers-areas in which high-quality international collaboration will be critical.