Gastric cancer and Helicobacter pylori: a combined analysis of 12 case control studies nested within prospective cohorts.
Level 3 - non-randomized controlled study
Pooled individual participant data meta-analysis of 12 nested case-control studies within prospective cohorts.
PubMed 11511555 · doi:10.1136/gut.49.3.347
What was done
A combined analysis of individual participant data from 12 case-control studies (10 published, 2 unpublished) nested within prospective cohorts. Eligible studies collected blood samples for Helicobacter pylori serology prior to gastric cancer diagnosis in cases. Matched odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the risk of gastric cancer overall, by anatomical subsite (cardia vs. non-cardia), and by time interval between blood sampling and cancer diagnosis.
What was found
Across 12 studies with 1,228 gastric cancer cases, H. pylori infection was significantly associated with non-cardia gastric cancer (OR 3.0, 95% CI 2.3–3.8). The association was stronger when blood samples were collected 10 or more years before cancer diagnosis (OR 5.9, 95% CI 3.4–10.3). H. pylori infection was not associated with altered overall risk of cardia cancer (OR 1.0, 95% CI 0.7–1.4).
Why it matters
This pooled analysis establishes that H. pylori selectively increases the risk of non-cardia gastric cancer and demonstrates that blood sampling close to diagnosis underestimates risk due to loss of infection/antibodies during cancer development.
Limits
The abstract does not report the total number of control subjects, specific demographic characteristics of the included cohorts, or adjustments for potential confounders such as smoking or diet. It also does not evaluate bacterial strain differences (e.g., CagA status).
Cited by
- supports The World Health Organization estimates that Helicobacter pylori colonization confers a 3- to 6-fold increased risk of gastric cancer.