Abstract
Helicobacter pylori is the major triggering factor for gastric carcinoma, but only a small proportion of infected patients develop this disease. Differences in virulence observed among H. pylori strains, namely in the vacuolating cytotoxin vacA gene, may contribute to this discrepancy. Infection with vacA s1, i1 and m1 strains increases the risk for progression of gastric premalignant lesions and for gastric carcinoma. However, in East Asian countries most of the H. pylori strains are vacA s1, regardless of the patients’ clinical status, and the significance of the vacA i1 and m1 genotypes for gastric carcinoma in this geographic area remains to be fully elucidated. The aim of the present study was to investigate this relationship in 290 patients from Macau, China. Using very sensitive and accurate genotyping methods, we detected infection with vacA i1 and with vacA m1 strains in, respectively, 85.2% and 52.6% of the patients that were infected with single genotypes. The prevalence of cagA-positive strains was 87.5%. No significant associations were observed between vacA genotypes or cagA and gastric carcinoma. It is worth noting that 37.5% of the infected patients had coexistence of H. pylori strains with different vacA genotypes. Additional studies directed to other H. pylori virulence factors should be performed to identify high risk patients in East Asia.
Highlights
Gastric carcinoma is the fifth most incident and the third most common cause of cancer-related death worldwide
Two hundred and eighty-one (96.9%) from a total of 290 patients included in the study were positive for H. pylori as shown by polymerase chain reaction (PCR)
The characterization of the vacA i-region was obtained in 272 (96.8%) of H. pylori-infected patients, in which 236 (86.8%) patients were infected with a single strain, while the remaining 36 (13.2%) were infected with multiple H. pylori strains
Summary
Gastric carcinoma is the fifth most incident and the third most common cause of cancer-related death worldwide. Half of the cases have occurred in East Asian countries, mainly in China, which has the highest estimated mortality rates (24 per 100,000 in men, 9.8 per 100,000 in women) [1]. The major risk factor for the development of gastric carcinoma is persistent Helicobacter pylori infection [2]. H. pylori induces chronic superficial gastritis that may evolve to chronic atrophic gastritis, intestinal metaplasia, dysplasia and to gastric carcinoma [3]. A small number of infected individuals will progress towards carcinoma, and it has been shown that disease development depends on the interplay between host genetic susceptibility, environmental factors, and bacterial virulence factors [4,5,6].
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