Exposure to the bacterium Helicobacter pylori is associated with roughly one in five colorectal cancer cases worldwide, according to a modeling study from the University of California San Diego published on September 8, 2026, in the journal eGastroenterology. The authors urge caution: this is a statistical association, not a causal relationship.
Helicobacter pylori is a bacterium that colonizes the gastric mucosa and is classified by the World Health Organization as a Group 1 carcinogen due to its established link to gastric cancer. Its role in colorectal cancer remains under debate despite growing evidence. In Mexico, the issue carries particular weight: UNAM reports, citing World Health Organization data, that approximately 70 percent of the Mexican population carries the organism, and that 90 percent of gastric cancer cases are associated with the infection. Gonzalo Castillo Rojas, a faculty member at UNAM's School of Medicine, noted that in 85 percent of those infected, the bacterium causes no symptoms or disease.
The study pooled 43 investigations covering data on 48,694,403 people. Exposure to the bacterium was linked to a 1.6 times greater risk of colorectal cancer. The global attributable fraction was 22 percent; when restricted to the 14 cohort and population-based studies, the figure dropped to 12 percent. Mongolia recorded the highest proportion, at 36 percent, while China had the greatest absolute number, with 139,619 cases. The pattern shifted by birth cohort: the fraction rose from 9.5 percent among those born before 1947 to 15 percent among those born between 1963 and 1977. Four observational studies found that antibiotic eradication was associated with lower risk, but only after 10 years.
The authors and specialists consulted by Infobae agree that randomized clinical trials are needed to determine whether eradication reduces risk, and the study warns that broad antibiotic use raises concerns about resistance and side effects. Those trials will determine whether eradication is incorporated into prevention guidelines.
This article was written with artificial intelligence assistance based on verified sources and reviewed by a human editor before publication.