Characterization of Gastric Cardia Tumors: Differences in Helicobacter pylori Strains and Genetic Polymorphisms.

Background: Gastric cancer results from a multifactorial process and is one of the most common causes of death worldwide. These tumors can arise in the distal stomach (non-cardia) and in the cardia region, presenting different characteristics and frequency of occurrence worldwide.

Aims: To search for differences between tumors of different locations that could explain the presence of cardia tumors, considering Helicobacter pylori strains and genetic polymorphisms.

Materials And Methods: DNA was extracted from gastric adenocarcinoma tissue of 127 patients. Helicobacter pylori genes were detected by PCR, and polymorphisms by PCR-RFLP.

Results: Most of the tumors were located in non-cardia. The genotype 28152GA of XRCC1 showed an increase in risk of cardia tumors. In analysis performed considering gender, women carrying TNF-308GA genotype showed a decreased risk of non-cardia tumors, while in men the decreased risk of non-cardia tumors was associated with TNF-308GG genotype. Genotypes combinations showed that the SNPs RAD51 135G>C, XRCC3 18067C>T, and XRCC1 28152G>A had some combinations more frequent in cardia tumors, with an increased risk. Patients infected by cagE-positive strains presented a positive correlation with non-cardia tumors.

Conclusion: The results showed some susceptibility differences between tumors of different locations. There was an increased risk relationship between three repair enzyme SNPs and cardia tumors, and the G allele of the cytokine gene TNF negatively influenced the development of non-cardia tumors. Helicobacter pylori strains seemed to be different in the cardia region, where they were less virulent than those located in the distal region of the stomach.