Compared to the low preoperative WBC group, the high preoperative WBC group exhibited higher expression of regulatory T cells (P = 0.0034), CD68+ macrophages (P = 0.0071), and CD66b+ neutrophils (P = 0.0041); increased expression of programmed cell death protein 1 (P = 0.005) and programmed cell death ligand 1 (P = 0.0019); and lower expression of CD8+ T cells (P = 0.0057) in colorectal cancer patients. This evidence concerns the gene PDCD1 and colorectal cancer.