Tumor-infiltrating lymphocytes (TILs) are vital components of the antitumor immune microenvironment, and are cellular basis of immunosurveillance against tumor cells.[45] CD4+ and CD8+ T lymphocytes induce cytotoxic cell death and inhibit tumor cell proliferation and migration in antitumor immunitive reaction.[46,47] Furthermore, lymphocytopenia has been clarified to be a prognostic factor of OS in PC.[48] Therefore, the ratio of increased platelets and decreased lymphocytes has prognostic value for patients with PC. This evidence concerns the gene CD4 and neoplasm.