Scientists studied how the bacteria living in our stomachs change as gastric (stomach) cancer develops. They looked at people with healthy stomachs, those with stomach inflammation, and those with stomach cancer. By analyzing bacteria and chemical compounds in their samples, researchers found that certain bacteria decrease while others increase as the disease progresses. They also discovered that helpful chemicals made by good bacteria drop significantly. These findings suggest that tracking changes in stomach bacteria and their chemical products might help doctors catch stomach cancer earlier, before symptoms appear.

The Quick Take

  • What they studied: How the types and amounts of bacteria in the stomach and gut change as stomach cancer develops, and what chemical changes happen along the way.
  • Who participated: The study included five groups of people: those with healthy stomachs, people with stomach inflammation, people with stomach lining damage, people with erosion (eating away of stomach lining), and people with stomach cancer. Exact numbers weren’t specified in the abstract.
  • Key finding: As stomach disease progresses, the variety of good bacteria decreases while harmful bacteria increase. Helpful chemicals called short-chain fatty acids (which reduce inflammation) drop significantly, while harmful inflammatory chemicals rise. A specific bacteria type called Actinobacteria was 93.5% accurate at identifying cancer patients.
  • What it means for you: This research suggests doctors might eventually use simple stool tests to detect early stomach cancer before symptoms appear. However, this is still early research—more testing is needed before this becomes a standard medical tool. If you have stomach problems, talk to your doctor about screening options.

The Research Details

Researchers collected samples from five different groups of people representing different stages of stomach disease progression. They used two main scientific tools: one that identifies and counts different types of bacteria (16S rRNA sequencing), and another that measures thousands of different chemical compounds in the samples (metabolomics). They analyzed both stool samples and stomach tissue samples to get a complete picture of what was happening at different disease stages.

The bacteria analysis looked at two things: how many different types of bacteria were present (diversity) and which specific bacteria were most common at each stage. The chemical analysis measured thousands of different molecules to see which ones increased or decreased as disease progressed. The researchers then used statistical tests to figure out which bacteria and chemicals were most important for identifying each disease stage.

This approach is important because it looks at the whole picture—not just bacteria OR chemicals, but how they work together. Previous research looked at these separately, but this study shows they’re connected. Understanding these connections helps scientists figure out exactly how stomach bacteria might contribute to cancer development, which could lead to better prevention and early detection methods.

This is an exploratory study, meaning it’s designed to discover patterns rather than prove cause-and-effect. The researchers used well-established scientific methods for identifying bacteria and measuring chemicals. The statistical tests they used (ROC curves showing 93.5% accuracy) suggest the findings are strong. However, the abstract doesn’t specify how many people participated, which makes it harder to judge how reliable the results are. The study appears to be from a reputable journal, but these findings need to be confirmed by other researchers before they become medical practice.

What the Results Show

The most striking finding was that bacterial diversity—the number of different types of bacteria—decreased significantly as stomach disease got worse, with the biggest drop happening at the atrophy stage (when the stomach lining thins). Certain ‘good’ bacteria like Bacteroides and Faecalibacterium became less common, while ‘bad’ bacteria like those in the Actinobacteria group became more common.

The chemical analysis revealed that helpful short-chain fatty acids (SCFAs)—chemicals produced by good bacteria that reduce inflammation—dropped significantly as disease progressed. At the same time, inflammatory chemicals that promote disease increased. The atrophy stage appeared to be a critical turning point where these chemical changes became especially noticeable.

When researchers looked at stomach tissue samples directly, they found even more dramatic chemical changes in cancer patients, affecting how cells use amino acids, energy, and other building blocks. The erosion stage (where the stomach lining wears away) showed a mix of early and advanced changes, suggesting it’s a transition point between early disease and cancer.

Two specific bacteria—Bifidobacterium and Oscillospiraceae—showed promise as markers of advanced disease stages. The study found that the atrophy stage (stomach lining thinning) was particularly important as a ‘breakpoint’ where the body’s chemistry shifted from relatively normal to cancer-like patterns. The erosion stage showed transitional features, meaning it had characteristics of both early and advanced disease.

Previous research had shown that stomach bacteria change in cancer patients and that chemical metabolism changes occur, but this study is novel in tracking both simultaneously across all stages of disease progression. It confirms earlier findings about bacteria changes while adding new information about how chemical compounds change in parallel. The identification of atrophy as a critical turning point is a new insight that could help doctors identify high-risk patients.

The abstract doesn’t specify the total number of participants, making it difficult to assess how reliable the findings are. The study is exploratory, meaning it identifies patterns but doesn’t prove that bacteria changes cause cancer—they could be a result of cancer rather than a cause. The research was likely conducted in specific geographic regions (possibly East Asia where stomach cancer is more common), so findings might not apply equally to all populations. The study used stool samples to represent stomach bacteria, but stomach bacteria might differ from gut bacteria. Finally, these findings need to be tested in larger studies and by other research groups before they can be used clinically.

The Bottom Line

Based on this research, there are no immediate changes people should make. However, if you have a family history of stomach cancer or live in a region where it’s common, discuss screening options with your doctor. This research suggests that in the future, simple stool tests might help identify people at risk, but that’s not available yet. For now, the standard recommendations remain: avoid smoking, limit alcohol, eat a diet rich in fruits and vegetables, and get tested for H. pylori infection if recommended by your doctor. Confidence level: Low to moderate—this is promising early research that needs confirmation.

This research is most relevant for people with a family history of stomach cancer, those living in East Asia or other high-risk regions, and people with chronic stomach problems. It’s also important for doctors and researchers working on cancer prevention and early detection. People with healthy stomachs don’t need to take action based on this single study, but understanding the connection between gut bacteria and cancer is valuable for long-term health.

If these findings lead to a clinical test, it would likely take 3-5 years of additional research before it becomes available. Even then, benefits would come from earlier detection rather than immediate symptom relief. The bacteria changes appear to develop over months to years as stomach disease progresses, so this isn’t something that changes overnight.

Want to Apply This Research?

  • Track digestive symptoms weekly (bloating, stomach pain, changes in appetite) and note any family history of stomach cancer. If a stool microbiome test becomes available, users could log results and track changes over time to monitor their digestive health status.
  • Users could set reminders to maintain habits that support healthy gut bacteria: eating fiber-rich foods (vegetables, whole grains, beans), staying hydrated, managing stress, and avoiding smoking. The app could provide recipes and meal ideas focused on foods that promote beneficial bacteria growth.
  • Establish a baseline of current digestive health through symptom tracking. If microbiome testing becomes available, users could test annually and track changes in bacterial composition and metabolite levels. The app could alert users if they develop persistent digestive symptoms that warrant medical evaluation, especially those with risk factors for stomach cancer.

This research is preliminary and exploratory in nature. The findings have not yet been confirmed by other independent studies and are not ready for clinical use. Do not use this information to self-diagnose or self-treat stomach problems. If you have symptoms of stomach disease (persistent pain, difficulty swallowing, unexplained weight loss, or vomiting), consult a healthcare provider immediately. The microbiome tests described in this research are not yet available for clinical diagnosis. Anyone with concerns about stomach cancer risk, especially those with family history or living in high-risk regions, should discuss screening options with their doctor. This article is for educational purposes only and should not replace professional medical advice.