A certain type of bacterium, known as Helicobacter pylori, is responsible for a range of ailments, including ulcers and, more alarmingly, gastric cancer. Recent results from a long-term study in China suggest that a short course of antibiotics and stomach acid reducers can effectively prevent cancer in those infected, even many years later.
The relationship between H. pylori infection and gastric cancer in India is complex. (Getty Images/iStockphoto)
H. pylori is a spiral-shaped bacterium that thrives in the stomach's acidic environment by neutralising the acid around it. It burrows into the stomach's mucus layer, evading the immune system. Despite its widespread presence, with around two-thirds of the global population carrying this bacterium, most people do not develop ulcers or gastric cancer.
Why some people suffer severe consequences while others remain asymptomatic is still a subject of ongoing research. Scientists have also been exploring ways to prevent more serious outcomes, like gastric cancer, from developing.
The discovery in the 1980s that H. pylori could cause ulcers revolutionised medical treatment for the condition. Barry Marshall and Robin Warren, who made this discovery, were awarded the 2005 Nobel Prize in Physiology or Medicine. Marshall famously drank a culture of H. pylori to prove that the bacterium could infect a healthy person and cause gastritis, which ultimately helped confirm H. pylori as the cause of peptic ulcers and gastric cancer.
However, it's still unclear why only a small fraction of the billions infected with H. pylori develop ulcers or cancer. The highest disease burdens are seen in East Asia, Latin America, and Eastern Europe.
Previously, small-scale studies and observational research, particularly in Japan, suggested that eradicating H. pylori might help prevent gastric cancer. Now, a comprehensive controlled trial has provided solid evidence supporting the effectiveness of widespread screening and eradication efforts. Published in Nature Medicine, the study shows that reducing the prevalence of H. pylori in a population can lead to a significant decrease in gastric cancer incidence over time.
In 2011, researchers conducted a large-scale study in China, visiting nearly a thousand villages and administering a simple breath test to more than 180,000 people. Over half tested positive for H. pylori. The study divided those infected into two groups: one received a 10-day course of antibiotics and stomach acid reducers to eradicate the bacterium, while the other did not.
More than a decade later, the results were striking. There was a 13% reduction in gastric cancer risk among the treated group and a 19% reduction among those who were cleared of the infection. Younger participants, particularly those under 45, experienced even more significant reductions in cancer incidence and mortality, suggesting that early intervention might be crucial in preventing cancer progression.
So, what are the implications for India? The relationship between H. pylori infection and gastric cancer in India is complex. While infection rates in India are high, ranging from 50% to over 80% in different communities, the rates of gastric cancer do not always correspond to this high prevalence.
For example, in India there is a higher incidence of gastric cancer in the southern regions compared to the North, suggesting that local factors (possibly dietary, environmental, or genetic) play a role.
Treating everyone infected with H. pylori may be impractical due to the costs associated with antibiotic treatments and the risk of antibiotic resistance. A more balanced approach might involve targeted intervention for those with ulcers and individuals at the highest risk of developing gastric cancer.
Overall, the importance of the new study is that it indicates that many lives could be saved by treating high-risk populations. The effect may be greatest in countries and regions where gastric cancers occur frequently such as in China where the authors note it is a “leading cause of cancer-related deaths.” In their research article, they estimate that H. pylori treatment “could reasonably expect to prevent >85,000 incident gastric cancer cases annually in China.”
Anirban Mahapatra is a scientist and author, most recently of the popular science book, When The Drugs Don’t Work: The Hidden Pandemic That Could End Medicine. The views expressed are personal.
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