A bacterial infection commonly found in the stomach may be linked to an increased risk of bowel cancer, according to a new international study. Researchers analyzing data from 48 million individuals report that exposure to Helicobacter pylori (H. pylori) bacteria is associated with a 1.59-fold higher likelihood of developing colorectal cancer.

H. pylori is a widespread bacterium, estimated to inhabit the stomachs of up to 40% of people in the United Kingdom. While often asymptomatic, the infection can lead to ulcers or inflammation of the stomach lining. It is already well established as a cause of stomach cancer, but its connection to bowel cancer has remained a subject of debate.

The analysis, conducted by teams from the University of Hong Kong and the University of California San Diego, reviewed 43 previous studies and was published in the journal eGastroenterology. Researchers estimated that approximately 22% of global colorectal cancer cases could be attributed to H. pylori exposure, assuming a causal relationship.

The study also examined the potential impact of treating H. pylori infections with antibiotics. Four included studies suggested that eradicating the bacteria might reduce the risk of bowel cancer, but this protective effect appeared only after a decade following treatment.

Furthermore, the research indicated that the proportion of colorectal cancers potentially linked to H. pylori infection has increased in more recent decades, particularly from the 1960s and 1970s onward. However, investigators emphasized that bowel cancer risk is influenced by multiple factors including genetic predisposition, age, lifestyle choices, and diet, underscoring the complexity of the disease’s causes.

In the United Kingdom, bowel cancer is the second leading cause of cancer-related deaths, accounting for nearly 18,000 fatalities annually. The findings underscore the importance of further research to clarify the role of H. pylori and whether targeted treatment strategies could contribute to bowel cancer prevention.