PDCD1 and gastric cancer: This study evaluated PD1/PDL1 expression in the microenvironment of MSI GC and analyzed its correlation with immune cell phenotypes to identify the cell types related to PD1/PDL1 expression in the microenvironment of MSI GC to better understand the interactions between tumor and immune cells and help select suitable target populations for future PD1/PDL1 immunotherapy in GC with different microsatellite statuses.