The pan-cancer tissues highly expressing pan-cancer tissue-enriched circRNAs tended to recruit a greater abundance of NK cells, neutrophils, pro-B cells, etc. The expression of pan-normal tissue-enriched circRNAs was positively correlated with a different group of tumor microenvironment cells, including the CD4+ T-cells, endothelial cells, and fibroblasts. This evidence concerns the gene CD4 and cancer.