Helicobacter pylori in gastric cancer established by CagA immunoblot as a marker of past infection

Gastroenterology. 2001 Oct;121(4):784-91. doi: 10.1053/gast.2001.27999.


Background & aims: Helicobacter pylori may disappear spontaneously with progressing precancerous changes and invalidate serologic studies of its association with gastric cancer. We reestimated the strength of the H. pylori-gastric cancer relationship, using both conventional immunoglobulin (Ig) G enzyme-linked immunosorbent assay (ELISA) and immunoblot (against cytotoxin-associated antigen A [CagA] antibodies that prevail longer after eradication) to detect past H. pylori exposure more relevant for time at cancer initiation.

Methods: In our population-based case-control study, the seroprevalence among 298 gastric adenocarcinoma cases was 72% (IgG ELISA) and 91% (immunoblot) vs. 55% and 56% among 244 controls frequency-matched for age and gender.

Results: Using IgG ELISA only, the adjusted OR for noncardia gastric cancer among H. pylori-positive subjects was 2.2 (95% confidence interval [CI], 1.4-3.6). When ELISA-/CagA+ subjects (odds ratio [OR], 68.0) were removed from the reference, the OR rose to 21.0 (95% CI, 8.3-53.4) and the previous effect modification by age disappeared. ELISA+/CagA- subjects had an OR of 5.0 (95% CI, 1.1-23.6). There were no associations with cardia cancer.

Conclusions: The weaker H. pylori-cancer relationships in studies based on IgG ELISA rather than CagA may be caused by misclassification of relevant exposure. A much stronger relationship emerges with more accurate exposure classification. In the general Swedish population, 71% of noncardia adenocarcinomas were attributable to H. pylori.

MeSH terms

  • Adenocarcinoma / microbiology*
  • Adenocarcinoma / pathology
  • Adolescent
  • Adult
  • Antigens, Bacterial / analysis*
  • Bacterial Proteins / analysis*
  • Child
  • Child, Preschool
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Helicobacter Infections / epidemiology*
  • Helicobacter pylori*
  • Humans
  • Immunoblotting
  • Immunoglobulin G / analysis
  • Infant
  • Male
  • Multivariate Analysis
  • Prevalence
  • Reference Values
  • Stomach Neoplasms / classification
  • Stomach Neoplasms / microbiology*
  • Stomach Neoplasms / pathology
  • Sweden / epidemiology


  • Antigens, Bacterial
  • Bacterial Proteins
  • Immunoglobulin G
  • cagA protein, Helicobacter pylori