Unhealthy Gut Microbiome Linked with Breast Cancer Spread in New Study

Problems with our gut microbiome, the microbes that live within our digestive system, are linked with many other health issues. In addition to digestive disturbances, an unhealthy microbiome may raise our risk of diabetes, allergy, inflammatory bowel disease, and colorectal cancer. Now, a new study finds it may also influence breast cancer spread.

Researchers at the University of Virginia Cancer Center recently investigated gut microbiome issues and their impact on mast cells in the breast. Mast cells are white blood cells that play an important role in our immune system. The team’s findings, published in the journal Cancer Immunology Research, showed that an unhealthy gut helped reprogram these cells to facilitate cancer spread.


Dr. Melanie Rutkowski, study co-author from the UVA Cancer Center, explains, “We show gut commensal dysbiosis, an unhealthy and inflammatory gut microbiome, systemically changes the mammary tissues of mice that do not have cancer. The tissue changes enhance infiltration of mast cells that, in the presence of a tumor, facilitate breast tumor metastasis. Mast cells recruited into the tissue environment during dysbiosis restructure the tissue architecture in such a way that tumor cells metastasize to other organs.”

The team discovered that these gut issues led mast cells to accumulate in the breast, which continued after the formation of hormone receptor-positive breast cancer in mice. The team says this made breast tissue a great spot from which cancer could continue its spread throughout the body. They also found that the mast cells increased collagen in the mice’s breast tissue and helped the cancer spread earlier. However, blocking the accumulation of mast cells stopped both from happening.

When they then looked for similarities in human breast tissue from patients with hormone receptor-positive breast cancer, they found that both mast cells and collagen were at increased levels, as well. They also determined that these higher collagen levels near tumors were linked with more mast cells and a higher risk of recurrence.


Dr. Rutkowski says, “Mast cells have had a controversial role in breast cancer, with some studies identifying a positive correlation with outcome while others have identified negative associations. Our investigation suggests that to better define the relationship between mast cells and risk for breast tumor metastasis, we should consider the mast cell functional attributes, tissue collagen density and mast cell location with respect to the tumor.”

She explains that if their findings are replicated, doctors may be able to target the gut-mast cell link to inhibit breast cancer spread and recurrence. It could also give clues on who is most at risk of their cancer returning.

Are you looking for ways to improve your gut health? Some things you can try are eating your vegetables, avoiding sugar and processed foods, introducing foods with prebiotics, eating more fermented foods, and exercising regularly.

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