A common bacteria found in the stomachs of millions could be a significant factor in the increasing rates of bowel cancer, according to new research published in the journal eGastroenterology. Scientists from the University of Hong Kong, in collaboration with experts from the University of California, analyzed data from over 48.7 million people across 43 studies worldwide.
The findings suggest that exposure to Helicobacter pylori (H. pylori), a bacterium that typically resides in the stomach's mucus lining, is associated with a 59% higher risk of colorectal cancer compared to individuals not exposed to it. H. pylori is known to cause indigestion, bloating, nausea, and ulcers, and is an established cause of stomach cancer. The researchers estimate that harmful strains of H. pylori might be involved in approximately 22% of bowel cancer cases, although this figure drops to around 12% when considering only the most robust studies.
The link appeared strongest in the Western Pacific Region, where H. pylori infections are more common, with researchers estimating that about a quarter of bowel cancer cases in this region could be linked to the bacteria. The bug is usually contracted in childhood and can persist for decades if untreated, leading to inflammation of the gut lining. Infection is often spread through poor sanitation, hygiene, and contaminated food or water, with vegetables like lettuce and spinach potentially becoming contaminated if washed or grown with infected water.
While H. pylori is a well-established cause of stomach cancer, its role in bowel cancer is still under investigation. However, the study noted that individuals whose H. pylori infections were eradicated with antibiotics showed a 10% lower risk of developing bowel cancer compared to those who remained untreated. The researchers concluded that treating the infection could potentially help reduce the risk of the disease in at-risk populations.
Colorectal cancer is one of several cancer types increasing among young people, and if current trends persist, it is projected to become the leading cause of cancer-related death among young adults by 2030. While obesity is a known risk factor, experts believe it alone cannot explain the overall rise.
Detection of H. pylori can be done through breath or stool tests, and treatment typically involves a seven-day course of triple therapy, combining acid-lowering medication with two antibiotics. Despite the suggestive findings, experts caution that the study does not definitively prove H. pylori causes bowel cancer, and further trials are needed to confirm if treating the infection can prevent the disease. Currently, other known preventable factors for bowel cancer include insufficient fiber intake, obesity, and heavy alcohol consumption.