CATEGORY: GUT & DIGESTIVE HEALTH
Pooling eight randomized trials covering 58,628 people, a short course of antibiotics to clear a common stomach infection was followed by 36% fewer stomach cancers than placebo or no treatment.1 The infection is Helicobacter pylori, a bacterium that settles in the stomach lining and is carried by roughly half the world’s population, usually without symptoms. Because the people in these trials were assigned to treatment or no treatment at random, this is stronger evidence than the observational studies that dominate this field.
Follow-Up Ran From 4 to 26.5 Years
Researchers gathered every randomized trial they could find in which adults confirmed to carry H. pylori were assigned either to eradication therapy—typically one to two weeks of antibiotics plus a drug that suppresses stomach acid—or to placebo or no treatment. What makes the pooled result meaningful is the length of the watch afterward: individual trials followed participants for anywhere from 4 years to 26.5 years, and new cancers were identified through national cancer registries and repeat endoscopies rather than by asking participants. Across the eight trials, 258 of 29,782 treated people developed stomach cancer, compared with 351 of 28,846 who were not treated.
About 228 Treated to Prevent One Stomach Cancer
That works out to 0.87% versus 1.2%—a 36% lower relative risk, with the pooled range running from 16% to 52% lower. Put another way, about 228 infected people would need to be treated to prevent one stomach cancer. Deaths from stomach cancer were also lower, 0.43% versus 0.56%, a 22% reduction, though that estimate sits closer to the edge of statistical significance and should be read as the less certain of the two. Preventing one death from stomach cancer would take treating about 812 infected people, far more than for preventing one cancer.1
The largest benefit was in people already treated for an early tumor
In three trials of people who had already had an early stomach tumor removed, new cancers occurred in 5.9% of those given eradication therapy and 11.4% of those who were not—a 48% reduction. In that group roughly 18 people would need treatment to prevent one new cancer.
All-Cause Deaths Were Unchanged, 11.8% Versus 12.1%
Deaths from all causes were unchanged: 11.8% versus 12.1%. The benefit here is specific to stomach cancer, not to living longer overall. Nearly all of these trials were run in East Asia, where stomach cancer is far more common than in the United States or Europe, so while the relative reduction may carry over, the absolute benefit in a lower-risk population would be smaller. Two of the eight trials were judged to be at high risk of bias, though restricting the analysis to the five strongest trials barely moved the result.
Untreated Infection, About Six Times the Stomach Cancer Rate
The same pattern shows up outside East Asia. In a US health-system study of 716,567 people tested for the infection, those who tested positive and went untreated had about six times the stomach cancer rate of uninfected people, while those who received eradication therapy had under three times—and the treated-versus-untreated difference emerged only after about eight years.2 That study followed people rather than assigning treatment, so it shows association rather than cause.
Key Takeaways
- Across eight randomized trials and 58,628 people, treating H. pylori infection was followed by 36% fewer stomach cancers and 22% fewer stomach cancer deaths.
- The effect was largest—a 48% reduction—among people who had already had an early stomach tumor removed.
- Deaths from all causes did not differ, and the trials were concentrated 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.