The Microbiome in Breast Cancer

Incidence of breast cancer is growing like cancer itself, unabated and mostly unpredictably (though diet, age and genetic predisposition are established risk factors.) As cancer of this type fells more women globally, solutions are urgent.

With the recent advances in analysis, the microbiome is under the microscope for its links to cancer. To be sure, the breast microbiome holds promise in prevention as well as therapy.

Jennifer Brubaker explored the issues nicely in an article titled The Breast Microbiome: A Role for Probiotics in Breast Cancer Prevention in Microbial Sciences.

Which bacteria are prevalent in breast tissue?

“A diverse population of bacteria can be found within breast tissue,” writes Brubaker “and this diversity is present irrespective of a history of lactation. In a study of 81 women in Canada and Ireland, the most abundant phylum in the healthy breast microbiome was Proteobacteria.”

When compared to women without breast cancer, more Enterobacteriaceae, Staphylococcus, and Bacillus occur in those with breast cancer. Interestingly, one well-known member of the Enterobacteriaceae, Escherichia coli (E.coli) may have links to cancer of the breast.

Microbe impact on therapies in breast cancer

• Cancer drugs may depend on healthy microbes for effectiveness.
• Bacteria may impact therapeutic response by changing the tumor microenvironment.
• Antibiotics can impact the effectiveness of chemotherapy, suggesting a microbial link.

Microbe impact on prevention of breast cancer

• Microbes alter immune response.
• Dysbiosis is linked to breast cancer.

Probiotics in prevention and treatment

Probiotics alter gut microbes. How beneficial this may be in cancer depends on a host of individual factors. Yet scientists know a few basic facts: Probiotics increase Bifidobacterium, a beneficial gut bacterium and decrease pathogenic E.Coli. Also, Lactobacillus and Lactococcus spp. are more common in healthy breast tissues than in cancerous tissues.

For a more nuanced appreciation, take a look at a 2017 podcast from the University of California San Francisco in which researchers discuss the human microbiome and breast cancer.

 “As we continue to learn more about the breast microbiome, it’s important to consider the interactions between various organs and microenvironments within the human body. Characterizing the human microbiome throughout the body may play an important role in calculating cancer risk, diagnosis, and prognosis.” Jennifer Brubaker