In the immune microenvironment we focus on the relationship between circRNA and macrophage M2 polarization, the expression of other immune cells associated with TME such as T cells, NK cells, and the surface immune checkpoint molecules PD-L1/PD-1 in tumor cells, and the expression of important components of TME: stromal cells such as cancer-associated fibroblasts, endothelial cells, and pericytes, for which more studies are needed to explore their potential regulation. Here, CD274 is linked to cancer.