In particular: (a) level of IL-17 mRNA in gastric tumors was associated with the depth of tumor, lymph-vascular invasion and lymph node involvement [68]; (b) gastric cancer patients have higher levels of IL-17 in serum and in cancer tissues than the general population [69]; (c) genetic data show that IL-17A and IL-17F polymorphisms increase gastric cancer risk [70]; (d) there are increased Th17 cells infiltrating tumors on patients with advanced gastric cancer [71]. This evidence concerns the gene IL17F and gastric cancer.