TNF genetic polymorphism (rs1799964) may modify the effect of the dietary inflammatory index on gastric cancer in a case–control study

The inflammatory process is known to increase the risk of gastric carcinogenesis, and both genetic and dietary factors are associated with inflammation. In the present study of 1,125 participants (373 cases and 752 controls), we determined whether the dietary inflammatory index (DII) is associated with the risk of gastric cancer (GC) and investigated whether a TNF polymorphism (rs1799964) modifies this association. Semi-quantitative food frequency questionnaire derived data were used to calculate the DII scores. Odds ratios (OR) and 95% confidence intervals (CI) were calculated using multivariable logistic models adjusted for confounders. When we stratified the data by sex, the association between GC and the DII was significant only among the women (OR, 2.27; 95% CI 1.25–4.19), and the DII effect on the risk of GC differed depending on the TNF genotype (OR, 2.30; 95% CI 1.27–4.24 in TT genotype; OR, 0.78; 95% CI 0.37–1.65 in CC + CT, p for interaction = 0.035). Furthermore, the association between the DII and GC was significant in the Helicobacter pylori-positive group; similarly, the effect differed based on the TNF genotype (OR, 1.76; 95% CI 1.13–2.73 in TT genotype; OR,0.98; 95% CI 0.54–1.77 in CT + CC, p for interaction = 0.034). In conclusion, rs1799964 may modify the effect of the DII on GC.