S100A8 and gastric cancer: CagA IgG serological status has been evaluated by ELISA using recombinant CagA in several gastric cancer case–control and cross-sectional studies to determine whether CagA IgG seropositivity is associated with an increased incidence of non-cardia gastric cancer relative to CagA seronegative H. pylori-positive individuals and age-matched uninfected controls [64,65,66,67,68,69].