Infecção por Helicobacter pylori e câncer gástrico: Freqüência de cepas patogênicas cagA e vacA em pacientes com câncer gástrico

Abstract

Background: The rates of Helicobacter pylori infection are very high worldwide, but only a minority of infected patients develop gastric carcinoma. This might be related, among several factors, to the colonization of the human stomach by pathogenic Helicobacter pylori strains. Objective: To investigate the distribution of cagA and vacA genotypes of Helicobacter pylori in paraffin-embedded gastric samples from patients with gastric cancer. Material and methods: Paraffin-embedded samples from 42 patients with gastric cancer were histologically examined and evaluated by PCR for H. pylori cagA and vacA (s and m regions) genotypes. Results: Histological analysis allowed direct visualization of H. pylori in 85.7% of cases and PCR for urease C gene detected H. pylori in 95% of cases. The presence of cagA gene was detected in 23 (54.7%) patients with gastric cancer. The s1 allele from vacA gene was found in samples from 24 (57.1%) patients and the m1 allele in 26 (61.9 %). The s1m1 genotype was detected in 24 (57.1%) patients with gastric cancer. The s2 allele was found in samples from four patients (9.5%) and the m2 allele in three (7.1%) patients. The distribution of H. pylori genotypes was similar in both intestinal and diffuse types of gastric carcinoma. Conclusion: Our results confirm the relevance of the pathogenic cagA and vacA H. pylori genotypes for significant organic lesions, such as gastric cancer, suggesting a possible role for H. pylori in the pathogenesis of gastric carcinoma.