In this study, to investigate the role of the tumor cell-intrinsic cGAS–STING pathway in the immune-active TME of dMMR GC, we assessed the tumor cell-intrinsic expression of cGAS–STING between pMMR/EBV (−) and dMMR GCs through immunohistochemistry (IHC) analysis of our own GC cohort. This evidence concerns the gene STING1 and neoplasm.