CXCL8 and gastric cancer: Previously studies indicated that the single nucleotide polymorphism (SNPs) of CXCL8 gene were significantly associated with increased risk or progression of non small cell lung cancer, gastric cancer, differentiated thyroid cancer and ovarian cancer, especially CXCL8-251 A/T (Rafrafi et al., 2013; Koensgen et al., 2015; Kilic et al., 2016; Boonyanugomol et al., 2019).