HKUMed-led study finds H. pylori may be linked to more than one in five colorectal cancer cases worldwide

On 28 September 2026, the LKS Faculty of Medicine at the University of Hong Kong (HKUMed) and the University of California San Diego reported that exposure to Helicobacter pylori may be associated with about 22% of colorectal cancer cases worldwide. The study is published in eGastroenterology.

H. pylori is already known to cause stomach ulcers and gastric cancer. The researchers say screening and eradication programmes set up to prevent gastric cancer may also help reduce colorectal cancer risk.

What the study found

• The team analysed 43 international studies covering about 48.7 million people, together with regional H. pylori prevalence and GLOBOCAN 2022 colorectal cancer data.
• People exposed to H. pylori had about 1.59 times the colorectal cancer risk of people without exposure.
• About 22% of colorectal cancer cases worldwide may be associated with H. pylori. In a narrower set of 14 population-based and cohort studies, about 12% of cases remained potentially linked.
• The Western Pacific region, including China, Mongolia and Vietnam, had the highest estimated share, about 25%. China had the largest number of cases potentially associated with the infection.

Why early detection matters

Professor Leung Wai-keung, Chair Professor of Gastrointestinal Medicine at HKUMed, noted that unlike many inherited cancer risks, H. pylori infection can be detected and treated. Observational studies suggest that people who received eradication treatment had a lower colorectal cancer risk after more than 10 years of follow-up. The authors say further prospective and interventional studies are still needed.

The estimated share of colorectal cancer linked to H. pylori was higher in later birth cohorts — about 9.5% for people born before 1947, and about 15% for those born between 1963 and 1977 — even as overall infection rates have declined.

The research team

The study was co-led by Professor Leung Wai-keung of HKUMed and Professor Shailja Shah of the University of California San Diego. Yunhao Li, a PhD student at HKUMed, is the first author. Collaborators included Erasmus MC in the Netherlands and Brown University in the United States.