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HKUMed-led international study finds Helicobacter pylori exposure may be associated with more than one in five colorectal cancer cases worldwide

28 September 2026

An international collaborative research study led by investigators from the LKS Faculty of Medicine of the University of Hong Kong (HKUMed) and the University of California San Diego, has found that exposure to Helicobacter pylori (H. pylori), a bacterium known to cause stomach ulcers and gastric cancer, may be associated with approximately 22% of colorectal cancer cases globally. The findings highlight the potential public health benefits of H. pylori screening and eradication programmes, which would help prevent gastric cancer and reduce the risk of colorectal cancer. The study was published in eGastroenterology [link to the publication]. 

Colorectal cancer is the second leading cause of cancer-related deaths worldwide. In 2022, nearly two million new cases and 900,000 deaths were reported globally, underscoring the urgent need to identify modifiable risk factors that could alleviate the disease burden. While H. pylori is an established gastric carcinogen, its role in colorectal cancer has remained controversial.

Identifying the risk of H. pylori in colorectal cancer
To better understand the potential impact of H. pylori exposure, the research team conducted a comprehensive analysis of data from 43 international studies involving approximately 48.7 million individuals. The analysis combined global and regional H. pylori prevalence estimates, with colorectal cancer incidence data from the Global Cancer Observatory (GLOBOCAN) 2022, examining variations by diagnostic method, sex and WHO region. 

The study found that H. pylori exposure was associated with a 1.59-fold increased risk of colorectal cancer compared to those without exposure. The researchers estimated that H. pylori exposure could potentially account for approximately 22% of global colorectal cancer cases. Even when analyses were restricted to 14 population-based and cohort studies, approximately 12% of cases remained potentially linked to H. pylori exposure.

Professor Leung Wai-keung, Li Shu Fan Medical Foundation Professor in Gastroenterology and Chair Professor of Gastrointestinal Medicine, Department of Medicine, School of Clinical Medicine, HKUMed, said, ‘Unlike many inherited cancer risks, H. pylori infection is both detectable and treatable. Our study suggests that H. pylori may contribute substantially to the global burden of colorectal cancer. Understanding this relationship could help inform future colorectal cancer prevention strategies and identify new opportunities to reduce the associated risks worldwide.’

The study also examined the impact of H. pylori eradication on colorectal cancer risk. Although evidence remains limited, existing observational studies indicate that people who received treatment to eliminate H. pylori experienced a lower risk of colorectal cancer after more than 10 years of follow-up. This highlights the importance of early detection and treatment and is consistent with the fact that colorectal cancer typically develops over many years. However, further prospective and interventional studies are required.

Exploratory analysis suggests variations in estimated H. pylori-related CRC burden across birth cohorts
The researchers observed that countries with higher H. pylori prevalence tended to have a greater estimated colorectal cancer burden associated with the infection. The Western Pacific region, including China, Mongolia and Vietnam, recorded the highest estimated proportion of colorectal cancer cases linked to H. pylori exposure, estimated at approximately 25%. China had the largest absolute number of colorectal cancer cases potentially associated with the infection.

The study also found that later birth cohorts appeared to carry a proportionally higher H. pylori-related colorectal cancer burden, despite a decline in prevalence. The estimated proportion increased from 9.5% among those born before 1947 to 15% among those born between 1963 and 1977, highlighting the need for further research into how infection, lifestyle and environmental factors may interact to influence cancer risk over time.

Dual benefits of H. pylori control
Many countries and regions have already introduced population-based H. pylori screening and eradication programmes to reduce gastric cancer risk. Professor Leung said, ‘The findings suggest that these programmes could potentially generate a dual cancer-prevention benefit by reducing the risks of both gastric cancer and colorectal cancer, particularly in areas where H. pylori infection remains highly prevalent and healthcare resources are limited.’ 

‘Our goal is to provide evidence that informs public health and research priorities and to guide infection-targeted prevention strategies at both global and regional levels, complementing and extending beyond H. pylori eradication efforts to reduce the risk of multiple cancers,’ added Professor Leung.

About the research team 
This was an international collaborative study involving researchers from the LKS Faculty of Medicine, the University of Hong Kong; the University of California San Diego; Erasmus MC in the Netherlands; and Brown University in the United States. The study was supervised by Professor Leung Wai-keung, Li Shu Fan Medical Foundation Professor in Gastroenterology and Chair Professor of Gastrointestinal Medicine, Department of Medicine, School of Clinical Medicine, HKUMed, and Professor Shailja Shah of the University of California San Diego, who are joint senior authors of the paper. The first author of the paper is Yunhao Li (PhD student, Department of Medicine, School of Clinical Medicine, HKUMed).