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Cancer research

Chemotherapy's Hidden Consequences: Oral Bacteria Found in Colon

Strategic Insights

— 1 min read

Researchers at the Fred Hutchinson Cancer Research Center have made a groundbreaking discovery that challenges our understanding of the microbiome and its role in the human body. By analyzing paired oral and fecal samples from patients undergoing intensive chemotherapy, scientists found that oral bacteria are indeed present in the colon, particularly in those with intestinal mucositis. This finding suggests that chemotherapy may have unforeseen consequences on the gut microbiome, with potential implications for patient health and treatment outcomes.

Key Takeaways:

  • The research identified a breakdown of niche separation in most patients undergoing chemotherapy, with oral bacteria colonizing the distal gut.
  • The extent of overlap between oral and gut microbiota increased with time, particularly in patients with intestinal mucositis.
  • The study used strain-level analysis of paired samples to demonstrate the presence of oral bacteria in the colon.
  • Financial supporters for this research include the National Heart, Lung, And Blood Institute, American Academy of Oral Medicine Research Advancement Committee, National Cancer Institute, and Kuni Foundation.
  • The study's authors believe that this finding may have consequences for the host, suggesting a potential link between chemotherapy and gut microbiome dysbiosis.
  • Intestinal mucositis, a common side effect of chemotherapy, was found to facilitate the colonization of oral bacteria in the distal gut.
  • The study's results provide direct evidence for ectopic colonization of the distal gut by oral bacteria in a disease state, highlighting the need for further research on the microbiome's role in chemotherapy-induced side effects.

Statistics:

  • 283 samples were collected from 39 patients undergoing intensive chemotherapy.
  • The study analyzed paired samples from saliva, plaque, and stool at four time points: baseline, week 2, week 3, and week 4 of chemotherapy.
  • The study found that 18 patients had intestinal mucositis at week 2, rising to 21 patients by week 3 and 10 patients by week 4.
  • The study's authors profiled the microbiota in 49, 51, and 43 samples from saliva, plaque, and stool, respectively.

Sources:

  • NewsRx. Researchers at Fred Hutchinson Cancer Research Center Zero in on Chemotherapy (Distal gut colonization by oral bacteria during intensive chemotherapy: direct evidence from strain-level analysis of paired samples). Health & Medicine Week. June 20, 2025; p 4180.
  • npj Biofilms and Microbiomes. Distal gut colonization by oral bacteria during intensive chemotherapy: direct evidence from strain-level analysis of paired samples. 2025,11(1):1-10. (Nature Portfolio)

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