A common bacterium, Helicobacter pylori (H. pylori), found in the stomachs of millions, may be partly responsible for the increasing rates of bowel cancer, according to new research. Scientists suggest H. pylori could be linked to as many as one in five cases of the disease. While around 40% of people carry the bacteria without symptoms, in some individuals it can lead to indigestion, bloating, nausea, and in severe cases, ulcers that may develop into stomach cancer.
The study, published in the journal eGastroenterology by researchers from the University of Hong Kong and the University of California, analyzed health data from over 48.7 million people across 43 studies. Their findings indicate that individuals exposed to H. pylori had a 59% higher risk of developing colorectal cancer compared to those not exposed. Based on the available data, researchers estimate that 22% of bowel cancer cases could potentially be associated with the bacteria, though this figure dropped to approximately 12% when considering only the most robust studies.
The link appeared most pronounced in the Western Pacific Region, where researchers estimate about a quarter of bowel cancer cases may be connected to H. pylori, potentially due to higher infection rates in these areas. H. pylori is typically contracted in childhood and can persist in the stomach for decades, causing inflammation of the gut lining. The exact mode of transmission remains unclear, but poor sanitation, hygiene, and contaminated food and water are considered common causes. Experts also caution that vegetables like lettuce, leeks, and spinach can become contaminated if grown or washed with infected water.
While H. pylori is a well-established cause of stomach cancer, its potential role in bowel cancer is under investigation. Some research suggests that treating H. pylori infections with a seven-day course of triple therapy, involving acid-reducing medication and two antibiotics, could reduce the risk of bowel cancer. Studies following participants for over a decade found that those who had the bacteria eradicated showed a 10% lower risk of developing bowel cancer compared to untreated individuals. However, experts emphasize that this work does not definitively prove causation and that further trials are needed to confirm if treating H. pylori infection actually prevents bowel cancer.
Colorectal cancer is among the types of cancer increasing in younger populations, with projections indicating it could become the leading cause of cancer-related death among young adults by 2030 if current trends persist. While obesity is a known behavioral risk factor, experts believe it alone cannot account for the overall rise, suggesting other factors like H. pylori may be involved. Cancer Research UK notes that over half of bowel cancers are preventable, with factors such as low fiber intake, obesity, and heavy alcohol consumption contributing significantly.