Role of the polymorphic IL‐1B, IL‐1RN and TNF‐A genes in distal gastric cancer in Mexico

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Abstract
Several cytokine gene polymorphisms have been associated with increased risk of distal gastric cancer (GC) and its precursor histological markers in Caucasian, Asian and Portuguese populations although little is known about their role in other ethnic groups. Our study investigates the role of the IL‐1B‐31, IL‐1RN and TNF‐A‐308 gene polymorphisms as risk factors for the development of GC in a Mexican population. We studied 278 patients who were enrolled at the Hospital Universitario Dr. José Eleuterio González, Universidad Autónoma de Nuevo León. The subjects were divided into 2 groups. Sixty‐three patients with histologically confirmed distal GC (mean age = 58.8 years, range = 22–84, F:M = 0.56), and 215 patients with no evidence of distal or proximal GC (mean age = 56.1 years, range = 18–92, F:M = 1.17). The IL‐1B‐31 and the TNF‐A‐308 polymorphisms were determined by PCR‐RFLP and pyrosequencing, respectively, in all cases and controls. The VNTR polymorphism in intron 2 of the 1L‐1RN gene was typed by PCR in 25 cases and 201 controls. The H. pylori status was determined by histology, rapid urease test, culture and serology for non‐cancer controls and by histology for the GC cases. The carriage of the proinflammatory IL‐1B‐31*C allele was associated with increased risk of distal GC (odds ratio [OR] = 7.63, 95% confidence interval [CI] = 1.73‐46.94, p = 0.003). When cases and controls were matched by age and gender, the OR value was higher (OR = 8.05, 95% CI = 1.8–50.22, p = 0.001). When only H. pylori GC cases and controls were compared, the OR value was 7.8 (95% CI = 1.05–161.8, p = 0.04). No association was found between any of the other polymorphisms studied and distal GC. In this Mexican population, the IL‐1B proinflammatory genotype increases the risk of distal GC. These findings are similar to previous reports in Caucasian populations and underscore the importance of cytokine gene polymorphisms in the development of distal GC.