Several genomewide association studies have been conducted in Chinese populations; they show that variants of IL‐23R, the subunit specific for the IL‐23 receptor, are associated with a significantly reduced risk of gastric cancer,65 but with a significantly increased risk of oesophageal cancer,66 hepatocellular carcinoma67 and acute myeloid leukaemia.68 However, the effect of these IL‐23R variants on the function of IL‐23 (eg, gain, loss or no effect) was not specifically described in the studies. This evidence concerns the gene IL23A and gastric cancer.