IL17 signaling plays a pivotal role in many autoimmune diseases (e.g., psoriasis, inflammatory bowel diseases, and spondyloarthropathies) as defense against pathogen insults (e.g., Candida, Cryptococcus, Klebsiella, and Staphylococcus) and human malignancies (e.g., prostate cancer, cervical cancer, esophageal cancer, gastric cancer, hepatocellular carcinoma, lung cancer, non-melanoma skin cancer, and colorectal cancer) [1,21,24,37,38,39,40]. This evidence concerns the gene IL17A and gastric cancer.