In this review, we summarized that in various diseases, including cancer, autoimmune and inflammatory diseases, microbial and parasitic infectious diseases, and other diseases, free dsDNA or CDNs derived from cancer cells, apoptotic or necrotic cells and pathogenic microorganisms could activate the cGAS-STING signal pathway of APCs to induce a series of immune cascades, producing various products such as type I IFN, pro-inflammatory cytokines and chemokines. This evidence concerns the gene CGAS and cancer.