A large-scale study confirms that the elimination of the bacterium Helicobacter pylori using antibiotic treatment significantly reduces the risk of stomach cancer.
It has long been believed that the stomach was sterile due to the highly acidic gastric secretions that made microbial growth impossible.
This dogma has, however, been shaken by the description of a new species of bacterium associated with stomach ulcers by Australian researchers Robin Warren and Barry Marshall in 1984 (1).
Initially, the discovery of this bacterium, later named Helicobacter pylori, was met with great skepticism by the medical community, the consensus at that time being that gastric ulcers were caused by stress, alcohol, or spicy food.
But subsequent work by Drs. Warren and Marshall definitively proved that this bacterium was the culprit (Dr. Warren even went so far as to deliberately ingest the bacterium to prove it!) and this major discovery was ultimately rewarded with the Nobel Prize in Medicine in 2005.
Inflammatory lesions
The presence of H. pylori in the stomach is explained by several adaptations of the bacterium that allow it to survive in this hostile environment.
It has a spiral shape that enables it to burrow through the mucus that coats the stomach wall (like a corkscrew), and simultaneously secretes an enzyme that converts urea into ammonia, thus forming an alkaline molecular shield that neutralizes stomach acidity.
When it manages to colonize the mucosa, inflammatory lesions (chronic gastritis) form, which can progress to ulcers or even worse, stomach cancer.
This carcinogenic effect of the bacterium is caused by the secretion of a toxin called CagA (cytotoxin-associated geneA) that penetrates the gastric mucosal cells and alters their structure and function.
Anti-cancer antibiotics
Despite its adaptation to the extreme conditions of the stomach, Helicobacter pylori remains a bacterium sensitive to certain currently available antibiotics, suggesting that it is possible to eradicate the infection and thus prevent the development of inflammatory conditions leading to cancer.
A very large-scale study conducted in China has just confirmed the anti-cancer effect of antibiotic treatment against H. pylori (2).
Initiated in 2011, this study first examined the presence of the bacterium in a population of 180,000 people, spread over 1,000 villages in the Shandong province (eastern China, south of Beijing). The research team then administered a combination of antibiotics and antacids to about half of the infected individuals (nearly 100,000 people) to rid them of the microbe (20 mg omeprazole, 750 mg tetracycline, 400 mg metronidazole, and 300 mg bismuth subsalicylate, for 10 days), while the other half received only a dose of antacids (omeprazole and bismuth salt) to relieve symptoms.
More than a decade later, the group reports today that this simple intervention reduced the risk of gastric cancer by 20% in the treated group with successfully eradicated H. pylori infection.
This risk reduction was even more significant in the subgroup aged under 45 at the start of the study, with a 35% reduction in the risk of gastric cancer.
It is therefore likely that the early eradication of the bacterium, before it can initiate sufficiently significant lesions to promote the onset of cancer, is necessary to prevent the progression of the disease.
Dr. Warren unfortunately passed away on July 23 at the age of 87, just a week before the publication of this important study. He leaves behind an invaluable scientific legacy, the positive impacts of which on human health are yet to be fully measured.
(1) Marshall BJ and Warren JR. Unidentified curved bacilli in the stomach of patients with gastritis and peptic ulceration. Lancet 1984; 1: 1311-5.
(2) Pan KF et al. Gastric cancer prevention by community eradication of Helicobacter pylori: a cluster-randomized controlled trial. Nature Medicine, published on July 30, 2024.
The Future of Gastric Cancer Prevention: A Bacterial Approach
Recent breakthroughs in the understanding of Helicobacter pylori (H. pylori) and its role in gastric health could herald a new era in cancer prevention strategies. As a bacterium previously shrouded in controversy, its confirmed link to stomach ulcers and cancer is reshaping medical research and public health approaches.
Innovative Antibiotic Therapies
The recent large-scale study conducted in China highlights the potential of targeted antibiotic treatments as an effective preventive measure against gastric cancer. This study suggests that eradicating H. pylori not only alleviates symptoms but importantly reduces cancer risk by 20%, with even more significant declines observed in younger cohorts. As antibiotic resistance becomes an increasingly pressing issue, the challenge will be to develop effective protocols that maximize efficacy while minimizing side effects.
Public Health Campaigns
The findings from this extensive research underscore the necessity for public health initiatives focusing on early detection and treatment of H. pylori infections. Community-based programs may facilitate screening in high-risk populations, particularly in regions with elevated rates of gastric cancer. These initiatives could mirror successful campaigns for other infectious diseases, promoting education around the long-term health risks associated with untreated H. pylori.
Personalized Medicine
As we advance in our understanding of the human microbiome, the future of gastric health may lean toward personalized medicine strategies. Tailored antibiotic regimens based on individual health profiles and genetic predispositions could optimize treatment outcomes. This personalized approach not only stands to improve eradication success rates but could also provide insights into preserving beneficial microbes within the gut flora.
Ongoing Research and Advancements
Continuous research into the mechanistic pathways through which H. pylori influences gastric pathology will be essential. Understanding how the bacterial toxins, like CagA, interact at the cellular level could lead to novel therapeutic targets. The tragic passing of Dr. Robin Warren serves as a reminder of the ongoing need for dedication in this research arena, paving the way for future scientists to build upon his monumental discoveries.