Breast Health & the Gut Microbiome

A growing body of evidence points to the intestinal microbiome as an important factor in both the initiation and metastasis of breast cancer. Data from a recent animal study published in Cancer Immunology Research supports the link between increased metastasis and gut dysbiosis, and suggests a novel mechanism for this link, specifically an accumulation as well as an alteration of function in mast cells found in mammary tissue.

In this study, dysbiosis was established in mice with antibiotic administration, and an increase in mammary mast cell abundance was observed. This correlated with increased mammary levels of specific chemokines, including CCL2 and CXCL10, which recruit inflammatory cells associated with metastasis. Mast cells were also found to be increased in the lungs of animals with mammary cancer, a common site of breast cancer metastasis, and the use of a mast cell stabilizer inhibited the dysbiosis-mediated tumor dissemination into the lungs. 

Additionally, mast cells from dysbiotic animals were shown to promote metastasis, while an equivalent number of mast cells from non-dysbiotic animals did not, suggesting functional changes in the mast cells of dysbiotic animals. Researchers also determined that dysbiosis-mediated mast cell activation led to greater fibrosis in mammary tissue, with a resulting increase in collagen. Importantly, tissue from human breast cancer showed an increased presence of mast cells, and a correlation with mammary tissue collagen levels. This study adds to a growing field which has recognized the importance of the gut microbiome in cancer risk, progression, and response to therapy.