Recent discoveries reveal the human microbiome’s emerging role in cancer progression and treatment.
The human microbiome, a diverse community of bacteria, viruses, fungi, and other microorganisms primarily in the gut, is increasingly recognised for its vital role in our overall health. Recent research shows that, beyond supporting digestion and immune function, the gut microbiome also influences cancer progression and treatment.
The Microbiome-Cancer Connection
Emerging evidence from the National Cancer Institute suggests that a person’s gut microbiome can influence the development of certain types of cancer, such as colorectal, liver, and stomach cancers. The microbiome produces metabolites that either promote or reduce inflammation, a key factor in cancer. Inflammatory molecules such as cytokines, produced by the microbiome, can damage DNA and create an environment favourable to tumour growth. However, beneficial bacteria can produce compounds like short-chain fatty acids which protect against inflammation and tumour formation.
A pivotal study from the University of Texas MD Anderson Cancer Center, found that patients with a more diverse gut microbiome responded better to immunotherapy for melanoma, suggesting that the microbiome may influence how the body responds to certain cancer treatments. As Dr. Jennifer Wargo explains, “You can change your microbiome, it’s really not that difficult, so we think these findings open up huge new opportunities.”
Microbiome and Cancer Immunotherapy
The microbiome can be used to enhance the effectiveness of cancer immunotherapies, which activate the immune system to target and kill cancer cells. While immunotherapy has transformed cancer treatments, only some patients respond well to it. A recent trial published in Science found that faecal microbiota transplants (FMTs) from patients who responded positively to immunotherapy boosted the immune response in patients who had not initially responded. Lead researcher Dr. Bertrand Routy mentions, “The faecal transplants resulted in remarkable clinical responses, suggesting that the microbiome plays an essential role in shaping patient outcomes.” Combining gut microbiome treatments with immunotherapy holds potential to improve cancer treatment success.
Probiotics and Prebiotics
In addition to faecal transplants, researchers are exploring how probiotics—supplements containing beneficial bacteria—and prebiotics—compounds that nourish these bacteria—
might modulate the microbiome to prevent or treat cancer. A study published in Cell Reports Medicine found that specific strains of probiotics could inhibit tumour growth in mice by reducing inflammation and promoting a healthier immune response.
This suggests that probiotics could enhance the efficacy of traditional cancer treatments.
However, some researchers also caution against the widespread use of over-the-counter probiotics without understanding their interactions with individual microbiomes. Dr. Rob Knight from the University of California San Diego notes, “There's very little evidence that taking bacteria improves your overall health, and marketing goes well beyond what the science says… It's important to remember that mice are not humans. Something may work very well in mice but that doesn't mean it will work on humans.” This underscores the need for further research before establishing probiotics as a standard medical treatment.
Biomarkers of Cancer
Recent research has highlighted the microbiome’s potential for early cancer detection and prevention. According to a study published in Nature Medicine, specific microbial signatures in the gut may act as biomarkers for early-stage cancer or indicate an individual’s cancer risk. This approach could lead to the development of non-invasive tests that analyse a person’s microbiome to identify early warning signs of cancer before tumours form.
Furthermore, scientists are studying whether lifestyle interventions, such as dietary changes that promote a healthy microbiome, can reduce cancer risk. A 2024 article from the Harvard T.H. Chan School of Public Health found that diets rich in fibre and fermented foods, which support a healthier microbiome, are associated with reduced inflammation and with a lower risk of chronic conditions including heart disease, type 2 diabetes, and certain cancers.
Conclusion
Microbiome research is poised to significantly impact oncology, from enhancing immunotherapy effectiveness to developing new biomarkers for early detection. As scientists delve deeper into the relationship between the gut microbiome and cancer, the future of personalised cancer therapies appears increasingly promising. However, further research is essential to fully understand how to optimise the microbiome’s role in cancer treatment and prevention strategies.
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