Its preoperative and perioperative prognostic value has been consistently demonstrated across multiple clinical studies.[28] To explore whether the prognostic utility of CA19‐9 is influenced by the TIME, we conducted an interaction analysis stratified by levels of tumor‐infiltrating GITR+ Tregs after adjusting for potential confounders, the analysis revealed a significant interaction between GITR+ Treg infiltration and the prognostic effect of CA19‐9 for both OS and RFS (p < 0.001 for both). Here, TNFRSF18 is linked to neoplasm.