CATEGORY: GUT & DIGESTIVE HEALTH
Roughly half the world carries Helicobacter pylori, a bacterium that settles into the stomach lining and usually causes no symptoms at all. It is also the leading known cause of stomach cancer. So one question has sat there for decades: if a short course of antibiotics clears the infection, do fewer people later get the cancer? Eight randomized trials covering 58,628 people now answer it. Pooled, treatment was followed by 36% fewer stomach cancers than placebo or no treatment.1 Nobody in these trials picked which arm they were in, which lifts the evidence above the observational work that fills most of this field.
Watched for Anywhere From 4 to 26.5 Years
Researchers gathered every randomized trial they could find in which adults confirmed to carry H. pylori were given either eradication therapy, typically one to two weeks of antibiotics plus a drug that suppresses stomach acid, or a placebo or nothing. The treatment itself is brief. What makes the pooled result mean anything is the length of the watch afterward. Individual trials followed participants for anywhere from 4 years to 26.5 years. New cancers were picked up through national cancer registries and repeat endoscopies, not by asking participants what had happened to them. Across the eight trials, 258 of 29,782 treated people developed stomach cancer against 351 of 28,846 left untreated.
0.87% Against 1.2%, and What That Costs in People Treated
That works out to 0.87% versus 1.2%, a 36% lower relative risk, with the pooled range running from 16% to 52% lower. Counted in people, about 228 infected adults would need treating to prevent one stomach cancer. Deaths from stomach cancer were lower too, 0.43% against 0.56%, a 22% reduction. That second estimate sits close to the edge of statistical significance and is the shakier of the two. Preventing one death would take treating about 812 infected people, far more than preventing one cancer.1
The Sharpest Effect Came After a Tumor Had Already Been Removed
Three of the trials enrolled people whose early stomach tumor had already been taken out. Among them, new cancers occurred in 5.9% of those given eradication therapy and 11.4% of those who were not, a 48% reduction. Roughly 18 people in that situation would need treatment to prevent one new cancer.
Living Longer Was Not Part of It
Deaths from all causes came out the same: 11.8% against 12.1%. The benefit is specific to stomach cancer. Nearly all of these trials ran in East Asia, where stomach cancer is far more common than in the United States or Europe, so the relative reduction may carry over while the absolute benefit in a lower-risk population would be smaller. Two of the eight trials were judged at high risk of bias, though dropping them and keeping the five strongest barely moved the result. The same pattern does turn up outside East Asia. A US health-system study tested 716,567 people for the infection. Those who tested positive and went untreated had about six times the stomach cancer rate of uninfected people. Those who received eradication therapy had under three times. The gap between treated and untreated emerged only after about eight years.2 That study followed people rather than assigning treatment, so it carries the weaker kind of evidence.
Key Takeaways
- Across eight randomized trials and 58,628 people, clearing H. pylori was followed by 36% fewer stomach cancers and 22% fewer deaths from stomach cancer.
- The largest effect, a 48% reduction, came in people who had already had an early stomach tumor removed.
- Deaths from all causes did not differ between treated and untreated groups.
- The trials sat overwhelmingly in East Asia, where stomach cancer is much more common than in Western countries.
References
- Ford AC, Yuan Y, Park JY, et al. Eradication Therapy to Prevent Gastric Cancer in Helicobacter pylori-Positive Individuals: Systematic Review and Meta-Analysis of Randomized Controlled Trials and Observational Studies. Gastroenterology. 2025;169(2):261–276. link
- Li D, Jiang SF, Lei NY, et al. Effect of Helicobacter pylori eradication therapy on the incidence of noncardia gastric adenocarcinoma in a large diverse population in the United States. Gastroenterology. 2023;165(2):391–401.e2. link.