Second, some single-nucleotide polymorphisms of some cytokines, such as polymorphisms of interleukin-8-251, interleukin-10-819, transforming growth factor beta1-509 and TNF-α-308, may exert their complex and interacting functions with each other, which could affect the effects of TNF-α-238 polymorphism in the pathogenesis of cancer. This evidence concerns the gene CXCL8 and cancer.