title: Relationship between cagA-positive Helicobacter pylori infection and risk of gastric cancer: a case control study in Porto Alegre, RS, Brazil.
abstract: BACKGROUND
  Gastric cancer is the second most common cause of cancer related death worldwide. Although Helicobacter pylori has been classified as a class I carcinogen, the presence of infection is not a factor that alone is able to lead to gastric cancer, and one of the possible explanations for this is the existence of different strains of H. pylori with different degrees of virulence.
  
  
  OBJECTIVE
  To investigate the association between cagA-positive H. pylori and gastric cancer, using polymerase chain reaction (PCR) for the detection of this bacterial strain.
  
  
  METHODS
  Twenty-nine patients with gastric cancer were matched by sex and age (± 5 years) with 58 patients without gastric cancer, submitted to upper gastrointestinal endoscopy. All patients were evaluated for the status of infection by H. pylori (through urease test, histological analysis and PCR for the genes ureA and 16SrRNA) and by cagA-positive strain (through PCR for cagA gene).
  
  
  RESULTS
  Evaluating the presence of infection by cagA-positive H. pylori, it was verified that the rate of infection was significantly higher in the group with gastric cancer when compared with the matched controls, occurring in 62.1% and 29.3%, respectively (OR = 3.95; CI 95% 1.543-10.096).
  
  
  CONCLUSIONS
  There is an association between cagA-positive H. pylori strain and risk of gastric cancer.
authors.affiliation: Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brasil. gilmeine@terra.com.br
authors.forename: Gilmara Coelho
authors.initials: GC
authors.lastname: Meine
authors.forename: Cláudia
authors.initials: C
authors.lastname: Rota
authors.forename: Judite
authors.initials: J
authors.lastname: Dietz
authors.forename: Setsuo
authors.initials: S
authors.lastname: Sekine
authors.forename: João Carlos
authors.initials: JC
authors.lastname: Prolla
mesh_terms: D000230:Adenocarcinoma / Q000382:microbiology*; D000293:Adolescent; D000942:Antigens, Bacterial / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D016022:Case-Control Studies; D005260:Female; D005838:Genotype; D016481:Helicobacter Infections / Q000150:complications / Q000382:microbiology*; D016480:Helicobacter pylori / Q000235:genetics* / Q000472:pathogenicity; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D011446:Prospective Studies; D012307:Risk Factors; D013274:Stomach Neoplasms / Q000382:microbiology*
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C080866:cagA protein, Helicobacter pylori