As shown in the Figure 9A, keyword clusters such as ′′tumor immunotherapy′′, ′′tumor microenvironment′′, ′′immune checkpoint inhibitors′′, ′′immunotherapy′′, ′′drug repurposing′′, ′′tumor-associated macrophages′′, ′′CD8(+) T cell′′, ′′lung cancer′′, ′′breast cancer′′, ′′photodynamic therapy′′, ′′chemoprevention′′, and ′′survival′′ highlight the prominence of metformin’s immune-mediated effects in tumor research. This evidence concerns the gene CD8A and lung cancer.