It is speculated that the mechanism of IL-17, which involves in development of colorectal cancer, is inhibiting proliferation and activation of NK cells, lymphocytes’ ability to secrete cytokines, and proliferation of T cells and facilitating angiogenesis of tumors, as well as inducing metastasis and infiltration of the nidus of colorectal cancer through cytokines (29). This evidence concerns the gene IL17A and colorectal cancer.