Examining the Role of Bacterial Biofilms in Colorectal Cancer Screening

Examining the Role of Bacterial Biofilms in Colorectal Cancer Screening

Recent researched has discovered that bacterial biofilms—structured communities of bacteria enmeshed in a self-produced matrix—are increasingly linked to colorectal cancer (CRC). A study published in Gut Microbes in January 2025 examines this connection in the context of biofilm epidemiology in over 2,000 individuals undergoing screening colonoscopy.

This information is a key development in CRC screening; by examining how bacterial biofilms colonize both normal colonic tissue and polyps and their influence on colorectal neoplasia, they may function as a biomarker. Additionally, examining how specific lifestyle, procedural, or demographic factors contribute to bacterial presence can aid further research. That being said, the distribution and relationship of bacterial microfilms to normal and abnormal tissues remain a subject of investigation.

Here’s a further look into the study, its findings, and its implications.

Design and Findings of the Trial

In terms of the study’s design, it leveraged biopsies from screening, surveillance, or diagnostic colonoscopies across three endoscopy centers. After strict exclusions—including pregnant patients, those with inflammatory bowel disease, or those using anticoagulants—histologically normal mucosa from all patients and polyps from a subset underwent detailed bacterial analysis via fluorescence in situ hybridization targeting bacterial 16S rRNA.

The study came to conclusions on a few key areas of interest. These include:

• Biofilm Presence and Colorectal Cancer: One of the most compelling aspects of this study was its analysis of biofilm presence on normal tissues in relation to polyp or cancer status. Surprisingly, individuals with polyps—regardless of histology—did not exhibit higher bacterial scores on adjacent normal tissue compared to polyp-free participants. However, those with newly diagnosed CRC did (p=0.006), suggesting that biofilms might align more closely with malignancy than with early neoplasia. In polyp tissues themselves, biofilm-positive polyps showed deeper crypt invasion and a strong correlation between bacterial score and polyp size (p=0.002). While this doesn't support biofilm presence as a direct marker for adenomas, it does suggest a co-evolution between microbial colonization and polyp progression.
• Impact of Procedural Variables on Detection: This study provided significant insight on how easily biofilm detection can be confounded by procedural factors. Variability in biopsy tools and bowel preparation techniques influenced bacterial detection, emphasizing the need for standardized methodologies to ensure consistency in future studies. For instance, more time from bowel prep to colonoscopy (p < 0.001) and use of larger forceps (p < 0.001) increased detection, while more aggressive preps suppressed it. Without consistent methodology, the use of biofilms as a biomarker becomes unreliable. Future protocols would need standardization or alternative sampling approaches—possibly utilizing pre-colonoscopy stool-based or mucosal lavage techniques—to overcome this.
• Influence of Lifestyle Factors: Smoking and alcohol consumption were linked to increased bacterial loads, whereas regular physical activity and a history of diabetes was correlated with lower bacterial presence.

Clinical Implications and Future Directions for CRC Screening

Taking a broader look at the potential impacts of this study, it’s important to note that while it reinforces an association between bacterial biofilms and CRC, it does not establish causation. The lack of a significant difference in bacterial presence between polyp-bearing and non-polyp-bearing individuals suggests that biofilms alone may not drive early-stage polyp development. However, the deeper bacterial invasion in larger polyps raises questions about whether biofilms contribute to malignant transformation or simply thrive in environments conducive to cancer growth.

Additionally, the study underscores the importance of standardizing colonoscopy procedures. Differences in biopsy techniques and bowel preparation methods were found to influence bacterial detection, which could lead to inconsistencies in research findings. Future studies should aim for uniform protocols to improve the reproducibility and clinical applicability of biofilm research in colorectal health.

But while these findings don’t place bacterial biofilms as standalone markers for early CRC screening, it strongly positions them as co-factors—possibly early accomplices—in mucosal transformation. If a causal relationship is established, biofilm detection could become an important tool for CRC risk stratification, potentially complementing existing screening methods.

References

Drewes JL, Rifkin SB, McMann M, et al. Epidemiology of bacterial biofilms on polyps and normal tissues in a screening colonoscopy cohort. Gut Microbes. 2025;17(1):2452233. doi:10.1080/19490976.2025.2452233