The association between the interleukin-1 polymorphisms and gastric cancer risk depends on the family history of gastric carcinoma in the study population

OBJECTIVES: The association between interleukin-1 polymorphisms, H. pylori and increased gastric cancer risk remains controversial. AIMS: To compare the prevalence of these polymorphisms in individuals with two mutually exclusive diseases connected with infection, gastric cancer, and duodenal ulcer. METHODS: 121 gastric cancer and 119 duodenal ulcer patients. Genomic DNA was typed for polymorphisms at position -511, -31 in the interleukin-1beta gene (IL-1 beta) using primer extension and mass-spectrometry. Analysis of the variable number of tandem repeats in intron 2, in its receptor antagonist gene (IL-1RN) was performed by PCR and agarose gel electrophoresis. RESULTS: All subjects were successfully genotyped for the three gene loci. IL-1 beta-511 was found to be in reverse linkage disequilibrium with IL-1 beta-31. The differences between gastric cancer and duodenal ulcer patients concerned only heterozygous variant of IL-1beta and were related to family history of gastric cancer, tumor stage, histology, site. Thus, CT carriers were found to have a higher risk of sporadic [OR 2.21 (95% CI, 1.22-3.99)], early [OR 2.81 (95% CI, 1.14-6.93)], diffuse [OR 2.48, (95% CI 1.21-5.09)] or non-cardia gastric cancer [OR 1.88 (95% CI 1.06-3.33)]. Furthermore, CT genotype was significantly more prevalent in gastric cancer patients with negative than in those with a positive family history (p = 0.039). CONCLUSIONS: The association between the interleukin-1 polymorphisms and gastric cancer risk depends on the family history of gastric carcinoma in the study population. This phenomenon may be in part responsible for differences in results of interleukin-1 studies performed on populations with low and high gastric cancer prevalence.