To investigate the expression level and prognostic significance of the costimulatory molecules in STAD, we selected nine CMGPs (CD276|LTBR, CD28|CTLA4, EDA|VTCN1, EDAR|TNFRSF19, FASLG|TNFSF8, PDCD1|TNFRSF9, TNF|TNFSF14, TNFRSF11B|TNFSF15, and TNFRSF18|TNFSF9). The gene discussed is TNFRSF9; the disease is gastric adenocarcinoma.