Interleukin 1B gene (IL-1B) and interleukin 1 receptor antagonist gene (IL-1RN) polymorphisms in Helicobacter pylori-negative gastric cancer of intestinal and diffuse histotype.

BACKGROUND: Polymorphisms in the interleukin 1beta gene (IL-1B-31T/C and IL-1B-511C/T single nucleotide changes) and in the interleukin 1 receptor anatagonist gene (IL-1RN2 variable number of tandem repeats) have been studied with respect to gastric cancer susceptibility. Available data support an aetiologic role of these genetic variants in the presence of concomitant Helicobacter pylori infection. Their contribution without H. pylori infection is still an open field of investigation.
MATERIALS AND METHODS: IL-1B and IL-1RN polymorphisms were investigated in 138 H. pylori-negative Italian patients with sporadic gastric cancer and 100 H. pylori-negative controls. Unconditional regression with odd ratios (OR) and 95% confidence intervals (CI), haplotype and linkage disequilibrium analyses were used to investigate the association of the polymorphisms with disease.
RESULTS: In all gastric cancer cases, carriers of the homozygous IL-1B-511T/T genotype showed a significant risk for the development of the disease (OR 3.2 with 95% CI 1.27-8.05). In cases with intestinal-type gastric cancer, however, both IL-1B-511T and IL-1RN2 alleles were associated with disease. In this subgroup, the odds ratio for carriers of both IL-1B-511T and IL-1RN2 was 6.49 (95% CI 2.07-20.4). Haplotype analysis supported the aetiologic contribution of these alleles in gastric cancer of the intestinal histotype.
CONCLUSIONS: In conclusion, IL-1B-511T and IL-1RN2 may contribute to intestinal gastric cancer risk in the absence of concomitant H. pylori infection. In this setting, future epidemiologic studies should consider dietary habits and exposure to carcinogens interacting with pro-inflammatory host genotypes.