Researchers found a promising new way to detect colon cancer and precancerous growths using a simple stool test. The test looks for a specific bacterial gene marker called m3 that appears more often in people with colon problems. In a study of over 2,500 people from China and Hong Kong, the test successfully identified colon cancer in many cases. Importantly, what people ate and the medicines they took didn’t affect the test results, making it reliable and practical for real-world use. This could eventually help doctors catch colon cancer earlier, when it’s easier to treat.

The Quick Take

  • What they studied: Whether a specific bacterial marker found in stool could reliably detect colon cancer and precancerous polyps, and whether diet or medications would interfere with the test.
  • Who participated: 2,563 people from China and Hong Kong, including 330 with colon cancer, 1,119 with precancerous growths (adenomas), and 1,114 healthy controls without colon problems.
  • Key finding: The stool test successfully identified colon cancer about 70% of the time and precancerous growths about 60% of the time. Diet and common medications did not affect the test’s accuracy.
  • What it means for you: This test could become a simple, non-invasive screening tool for colon cancer that doesn’t require uncomfortable procedures. However, it’s not yet ready for widespread use and needs more testing before doctors can rely on it alone.

The Research Details

Researchers conducted a prospective cohort study, meaning they followed groups of people forward in time and collected information about them. They recruited 2,563 participants from two locations in China and Hong Kong. Before people had their colonoscopies (the standard camera procedure to look inside the colon), researchers collected stool samples and asked about their diet. They measured the m3 bacterial marker in the stool using a laboratory technique called quantitative PCR, which counts how much of the marker is present. They compared the marker levels between people with colon cancer, people with precancerous polyps, and healthy people without any problems.

The researchers also tested whether common foods (meat, vegetables, and oils) and 15 different medications would change the m3 marker levels. They did this both in laboratory experiments and by analyzing real patient data while accounting for other health factors. This two-pronged approach helped them understand whether the test would be reliable in everyday situations.

This research approach is important because any new medical test needs to work reliably in real people, not just in laboratory conditions. By testing whether diet and medications affect the marker, the researchers showed that the test is stable and dependable. This makes it more likely to be useful as a screening tool that doctors could recommend to patients.

This study has several strengths: it included a large number of participants (2,563), used multiple independent groups from different locations, and tested the marker in both laboratory and real-world conditions. The researchers carefully adjusted their analysis for other factors that might affect results. However, the study was conducted only in China and Hong Kong, so results might differ in other populations. The test’s ability to detect precancerous growths (60%) is moderate, meaning it would miss some cases. More research is needed before this test can replace colonoscopy screening.

What the Results Show

The m3 bacterial marker showed good ability to distinguish colon cancer from healthy people, with a success rate of 70% (measured as an AUROC of 0.701). This means if you had the test, there would be a 70% chance it would correctly identify whether you had colon cancer or not. For precancerous growths called advanced adenomas, the test was moderately successful at 60% accuracy (AUROC of 0.604). Both of these results were statistically significant, meaning they’re unlikely to have happened by chance.

When researchers looked at whether diet affected the test, they found no meaningful impact. They tested three major dietary components—meat, vegetables, and oils—and none of them changed the m3 marker levels in laboratory experiments. Similarly, when they analyzed real patient data and adjusted for other health factors, diet did not significantly affect the test results.

The study also examined 15 commonly used medications, including drugs for blood pressure, cholesterol, diabetes, and other conditions. None of these medications significantly altered the m3 marker levels in either the laboratory tests or the patient analysis. This is important because it means people wouldn’t need to stop taking their regular medications before getting this test.

The researchers found that the m3 marker was particularly good at detecting colon cancer specifically, performing better for cancer than for precancerous polyps. This suggests the marker might be most useful as a tool to identify people who definitely need further evaluation. The fact that clinical factors (like age, gender, and other health conditions) didn’t significantly change the relationship between the marker and colon disease suggests the test could work similarly across different groups of people.

This research builds on earlier work showing that certain bacteria in the gut are associated with colon cancer. The m3 marker appears to be a more specific and reliable indicator than some previous bacterial markers studied. The study’s finding that diet and medications don’t interfere is particularly valuable because previous research on gut bacteria sometimes showed that these factors could affect results. This makes m3 a more practical choice for a screening test.

The test’s accuracy for detecting precancerous growths (60%) is not high enough to use it alone for screening—many cases would be missed. The study was conducted only in Chinese populations, so we don’t know if the results apply equally to other ethnic groups or geographic regions. The researchers collected dietary information using a simple questionnaire rather than detailed food tracking, so they may not have captured all dietary effects. Additionally, this was a one-time measurement study, so we don’t know how the marker changes over time or how often people would need to be tested. Finally, the study didn’t compare the m3 test directly to other new screening methods that are being developed.

The Bottom Line

Based on this research, the m3 stool test shows promise as a potential screening tool for colon cancer, but it is not yet ready for routine clinical use. Current evidence suggests it could be most useful as an additional test to help identify people at higher risk who should get a colonoscopy. People should continue following standard colon cancer screening guidelines (colonoscopy starting at age 45-50) until this test is further validated and approved by health authorities. The test appears reliable regarding diet and medication interactions, which is encouraging for future development.

This research is most relevant to people over 45 who are considering colon cancer screening options, people with a family history of colon cancer, and healthcare providers looking for better screening methods. It’s less immediately relevant to younger people without risk factors, though they may benefit once the test is fully developed. People with inflammatory bowel disease or other colon conditions should discuss screening options with their doctors regardless of this research.

If this test is further validated and approved, it could potentially become available within 2-5 years. However, even then, it would likely be used alongside colonoscopy rather than replacing it. People should not expect to see this test widely available in their doctor’s office immediately based on this single study.

Want to Apply This Research?

  • Track your colon cancer screening status and dates. Users can log when they had their last colonoscopy and set reminders for when they’re due for the next screening based on their age and risk factors. Once the m3 test becomes available, they could also track results from that test.
  • Use the app to maintain a record of colon cancer risk factors (family history, age, diet quality) and set reminders for screening appointments. Users can also track lifestyle factors like physical activity and diet that are known to reduce colon cancer risk, even though this specific test isn’t affected by diet.
  • Create a long-term screening timeline in the app that shows recommended screening intervals based on current guidelines. Users can receive notifications when they’re approaching their screening date and log results once testing is completed. This helps ensure people don’t miss important preventive care.

This research describes a promising experimental test that is not yet approved for clinical use. It should not be used to replace standard colon cancer screening methods like colonoscopy. If you have concerns about colon cancer risk or screening, please consult with your healthcare provider about appropriate testing options for your individual situation. This information is for educational purposes only and does not constitute medical advice.