H pylori tied to one in five colorectal cancers

Clinical takeaway: This modeled estimate strengthens the case that H pylori eradication may pay a dividend beyond gastric cancer prevention.

Colorectal cancer is the second leading cause of cancer death in the US, and incidence is climbing among younger adults. Screening now starts at 45, but without a settled explanation for the observed shift. Most of the disease's modifiable risks run through diet and lifestyle, which are slow and hard to change. An infectious contributor would be a different kind of target. Infections can be found with a test and cleared with a course of therapy, a lever primary care already knows how to pull. 

Helicobacter pylori is already a group 1 carcinogen with an established causal role in gastric cancer and its precursor. Whether the bacterium's reach extends below the stomach has been argued for decades. Study after study found more colorectal cancer among infected people, but no one had quantified what that association would mean for the disease's toll. A new risk attribution modeling study takes the question on directly. It delivers the most comprehensive estimate to date of how much colorectal cancer might trace back to a single treatable infection, and where that burden falls. 

Across the pooled data, H pylori exposure was associated with a 1.59-fold higher risk of colorectal cancer, with the plausible range running from 1.36- to 1.87-fold, and the association held across most subgroups. Applied to global 2022 case counts, the model put an estimated 22% of colorectal cancers worldwide, roughly 430,000 cases, as potentially related to exposure. That share fell to 11.9% when the analysis was restricted to the 14 population-based and cohort studies, with an uncertainty interval wide enough to include almost no attributable cases. 

For US patients, the modeled share was about 9%, among the lowest of any country examined. Attributable burden concentrated instead where H pylori prevalence runs high and colorectal cancer incidence runs low: the Western Pacific region carried the highest share at 25.1%. Treating the infection was associated with a 10% lower colorectal cancer risk, but only in studies following patients for more than 10 years. At shorter follow-up, risk did not appear to change.

The researchers pooled 43 observational studies covering 48.7 million people, combined the resulting risk estimates with global H pylori prevalence data from their prior meta-analysis, and applied the model to GLOBOCAN 2022 cancer figures using Monte Carlo simulation. The restricted analysis drew on the 14 population-based and cohort studies, with median follow-up of 14 years. The eradication finding rests on two cohort studies with more than 10 years of follow-up; heterogeneity across the full evidence base was substantial. 

Half the world already carries H pylori, and the playbook for finding and clearing it exists today. The authors argue that a definitive trial requires predefined colorectal outcomes and follow-up past 10 years. Mass eradication also carries costs that grow with its reach, chiefly antibiotic resistance and treatment side effects.

"H. pylori exposure may meaningfully contribute to global CRC burden with the extent of preventable burden dependent on the causal nature and other modifying variables related to H. pylori exposure (eg, timing, duration)," the authors conclude.

Source: Li Y, et al. (2026 Sep 8) eGastroenterology. Global and regional burden of colorectal cancer potentially related to Helicobacter pylori exposure: a risk attribution modelling study