In recent years, experts in the field of GC research have pointed out that parameters reflecting individual immune status, such as preoperative systemic immune-inflammation index (SII) [30], Follistatin-like 1 (FSTL1) [31], immune T cell subsets (including CD3+, CD4+, CD8+, CD4+/CD8+ ratio, NK Cells) [32], the preoperative and the postoperative neutrophil-to-lymphocyte ratios (NLR) [33–36], and platelet-lymphocyte ratio (PLR) [37], may be useful prognostic indicators of GC. This evidence concerns the gene CD8A and gastric cancer.