PDCD1 and colorectal cancer: The three oncogenes, Cytotoxic T Lymphocyte Associated Antigen 4 (CTLA-4), Programmed death-ligand 1 (PD-L1), and Programmed Cell Death Protein 1 (PD1), were primarily concerned with promoting the growth of colorectal cancer (CRC), worsening inflammatory reactions, and metastasis through the secretion or activation of cytokines and chemokines in the tumor microenvironment16–19.