The main findings of the current study are as follows: (1) LAG3 + immune cell density differs significantly between PR-GC and NAT-GC; (2) LAG3 + cell density shows significant differences in spatial distribution patterns between tumor compartments in PR-GC, which is not seen in NAT-GC; (3) CSS is significantly longer for patients with LAG3 expression above the calculated cut-offs in both cohorts; (4) LAG3 + immune cell density in TC is an independent prognostic factor of CSS in NAT-GC. This evidence concerns the gene LAG3 and gastric cancer.