Plummer M et al. (2007) Helicobacter pylori cytotoxin-associated genotype and gastric precancerous lesions. J Natl Cancer Inst 99: 1328–1334

Infection with Helicobacter pylori is known to be associated with an increased risk of gastric adenocarcinoma. Nevertheless, it is rare for gastric adenocarcinoma to develop in response to H. pylori infection; persistent infection more usually causes gastritis, peptic ulcer disease or atrophic gastritis. The factors that determine the link between infection and risk of gastric cancer are complex and not well understood, possibly relating to both the genetic background of the individual, and to the genetic variation of H. pylori.

Strains of H. pylori that carry the cytotoxin-associated (cagA) gene are more virulent and cause infections that are more likely to lead to atrophic gastritis and gastric cancer. In this study, Plummer et al. investigated the relationship between cagA-positive H. pylori infection and the degree of change observed in the gastric mucosa in samples of precancerous lesions of the stomach. These precancerous samples were collected from 2,145 patients as part of a chemoprevention trial in Venezuela, a region where H. pylori infection is common.

Analyses of samples taken at enrollment showed that dysplasia was markedly more common in patients infected with cagA-positive H. pylori than in those infected with cagA-negative strains. Individuals in the cagA-positive group were also more likely to experience progression of their precancerous lesion and were less likely to experience regression. The authors conclude that infection with cagA-positive strains of H. pylori could be a strong predisposing factor for the development of gastric adenocarcinoma.