Association of the myeloperoxidase polymorphism with the risk of gastric cancer.

Background: The myeloperoxidase in neutrophils manufactures many bactericidal oxidants. The aim of this study was to clarify the relations between the myeloperoxidase polymorphism and gastric cancer development. Patients and Methods: In a case control study of 157 consecutive gastric cancer patients and 192 controls, the myeloperoxidase -463G→A polymorphism was genotyped. Additionally, gastric mucosal changes were examined according to the updated Sydney System. Results: The carriage of myeloperoxidase allele A, male gender, advanced age, high intake of salty food and Helicobacter pylori infection independently increased the risk of gastric cancer [95% confidence interval (CI): 1.5-5.0, 1.7-6.5, 2.6-8.6, 1.1-2.6 and 1.2-3.8, respectively]. H. pylori-infected individuals who were carriers of myeloperoxidase allele A had increased risks of both intestinal and diffuse types of gastric cancer with odds ratios of 7.9 (95% CI 2.6-23.5) and 8.6 (95% CI 2.0-36.7), respectively. In the H. pylori-infected individuals, allele A carriers displayed higher scores of bacterial density (p=0.02) and neutrophil infiltration (p=0.05) in the antrum and higher scores of neutrophil infiltration (p=0.02) and gland atrophy (p=0.03) in the corpus than did non-carriers. Conclusion: This study verifies the association of myeloperoxidase -463 G→A polymorphism with gastric cancer. The mechanisms underlying this genetic polymorphism in developing gastric cancer merit further investigations.