PDCD1 and gastric adenocarcinoma: Given the significance of immune checkpoint inhibitor-based immunotherapy, the expression levels of nine immune checkpoint molecules (CD28, CTLA4, CD274, HAVCR2, BTLA, TNFSF4, CD160, PDCD1, and TGFBR1) and nine chemokines (CCL2, CCL17, CCL18, CCL22, CCR2, CCR5, CCR6, CXCL12, and CXCR4) that were closely associated with immune cell recruitment between the low- and high-risk groups were compared to evaluate the responses of STAD patients to immunotherapy.