Bacteria in Gut Improves Cancer Treatment

The mere presence of certain gut bacteria significantly affects the success of certain cancer treatments, according to two recent studies appearing in Science. Previous studies have revealed similar evidence that the inflammatory response to certain bacteria is beneficial in some therapies; however, the new studies represent an essential extension of this research, making it increasingly clear that the gut microbiome plays a major role in inflammation and immunity, and potentially general health.

Researchers observed that gut microbes seem to control the host immune responses triggered by cyclophosphamide, an anticancer drug, and specific immunotherapy and chemotherapy treatments in cancer mouse models. Both studies revealed that germ-free or antibiotic-treated mice responded with less success to tumor-targeting therapies than those with rich and diverse gut microbiomes.

Often, we think about the gut microbiome influencing only surrounding intestinal organs. These novel concepts of the microbiome affecting the entire body as a whole is groundbreaking. Both studies are very exciting in that they show initial correlations between gut microbiota and response to therapies and harness our microbiome to help us fight cancer. Conversely, dybiosis might make fighting cancer harder. The research results highlight the importance of microbes in shaping not just our risk of disease, but our recovery from it.


Iida, N., et al., “Commensal bacteria control cancer response to therapy by modulating the tumor microenvironment,” Science, 342:967-70, 2013. <>

Viaud et al., “The intestinal microbiota modulates the anticancer immune effects of cyclophosphamide,” Science, 342:971-76, 2013.

Tracy, Vence. "Gut Flora Boost Cancer Therapies." The Scientist. 2013. Accessed January 20, 2016.

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