Figure 9 visually represents the key areas and future directions of research on Treg and BC over time. The Cluster ID indicates the specific clustering number. The clusters are represented as # 0, # 1, # 2, and so on, with the size of each cluster indicating the number of members it contains. In Figure 9, there are eight clusters identified, covering topics such as immunotherapy, immune evasion, interleukin-2 regulation, prognosis, PD-1, CCR6, immune status, and CD4(+) T cell. This evidence concerns the gene CD4 and breast cancer.