PTGER3 and neoplasm: Based on the results of multivariate Cox regression analysis, a prognostic index for STAD tumor samples was established based on the formula immune-related gene prognostic index (IRGPI) = expression level of RNASE2* 0.277 + expression level of CGB5* 0.255 + expression level of INHBE*0.501 + expression level of PTGER3*(– 0.348) + expression level of CTLA4*(– 0.341) + expression level of DUSP1*0.260 + expression level of APOA1*0.071 +  + expression level of CD36*0.234.