A new modelling study suggests that infection with Helicobacter pylori, the stomach bacterium best known for causing ulcers and gastric cancer, could be tied to roughly one in five colorectal cancers worldwide. The headline estimate is 22%. Early findings suggest the true share may be much lower, and the authors say so themselves.
The work, a risk-attribution analysis published in eGastroenterology, pooled 43 studies covering 48,694,403 people. Across them, exposure to H. pylori went with a 1.6-fold higher risk of colorectal cancer. The researchers combined that with 2022 incidence data from the Global Cancer Observatory, which counted about 1.9 million new cases and more than 900,000 deaths worldwide that year.
Why 22% needs caution
The figure moves a lot depending on which studies are counted. When the team limited the analysis to 14 population-based and cohort studies, the attributable share fell from 22% to 12%. That gap shows how study design and selection can shape a burden estimate. The authors stress that prospective studies are needed before H. pylori can be called a cause, or a modifiable risk factor, for colorectal cancer.
The analysis found no statistically significant differences by sex, by age above or below 60, by the test used to detect the bacterium, or by whether a country runs a national screening program. Regional differences were sharper. The Western Pacific had the highest regional estimate, at about 25%, and Mongolia the highest national one, at 36%. China had the largest absolute number, with 139,619 cases potentially linked to exposure. An exploratory look at birth cohorts suggested the share rose from 9.5% among people born before 1947 to about 15% for those born from 1963 through 1977, though the researchers say that pattern needs confirmation.
What earlier research shows
Other work points the same way, with caveats. A US Veterans Health Administration cohort followed 812,736 people who were tested for H. pylori, 205,178 of them positive. Over up to 15 years, a positive result was linked to an 18% higher risk of colorectal cancer and a 12% higher risk of dying from it. Among those who tested positive, going untreated was associated with more cancers and deaths than receiving treatment.
Two randomized trial cohorts gave mixed results. In one, treatment was associated with lower colorectal cancer risk over 29.4 years. In the other, there was no overall benefit after 13.8 years, and any benefit seemed limited to people with high genetic susceptibility or antibodies to particular H. pylori antigens. Diet, income and access to care can all travel alongside H. pylori and blur these associations.
What this means for patients
Current treatment guidelines target H. pylori for stomach conditions and gastric cancer prevention, not for colorectal cancer. The American College of Gastroenterology recommends 14 days of bismuth quadruple therapy as the preferred first regimen for many adults who have not been treated before, with a check at least four weeks afterward to confirm the bacteria are gone. Clarithromycin-based triple therapy should be avoided unless testing shows the bug is sensitive to it.
The analysis does not support treating everyone for H. pylori just to prevent colorectal cancer, since broad programs could increase antibiotic use, side effects and resistance. Screening for colorectal cancer should continue as recommended whatever a person’s H. pylori status. The encouraging part is that this is a lead worth following. If you have stomach symptoms or questions about testing, talk to your doctor.
