Poor gut health and the risk of aggressive breast cancer

Not long ago, researchers discovered that, like the gut, the breast has its own microbiome. And certain changes in that collection of microorganisms, such as lower levels of the friendly bacteria Lactobacillus and higher levels of Escherichia coli and Staphylococcus epidermidis, can increase the risk of breast cancer.

But that’s not the only microbiome that influences breast health. Some investigators believe the part of the gut microbiome known as the estrobolome may also play a strong role in the development of breast cancer.

The estrobolome has bacteria that can break down estrogen so that it’s easily expelled from the body. And since estrogen fuels about 70 percent of breast cancers, keeping the estrobolome healthy could help protect against the disease.

One study in mice found that changing the gut microbiome resulted in breast tissue inflammation, which led to more aggressive breast cancer. Other studies showed the health of the gut microbiome could affect how well certain breast cancer treatments work.

Now, another study by the UVA Cancer Center adds even more credence to the gut-breast cancer connection….

Bad gut health can trigger mast cell buildup in the breast

This latest study uncovered a complex set of interactions between the microbes in the gut and the breast’s mast cells. These blood cells help manage the body’s immune response to disease and allergens.

The research team found that an unhealthy microbiome triggered an accumulation of mast cells in the breast. These changes continued after tumors formed in a mouse model of hormone receptor-positive breast cancer, which could spark the cancer’s spread into other parts of the body.

The researchers also discovered the mast cells increased how much collagen was found in the mice’s breast tissue, spurring earlier cancer spread.

By blocking the mast-cell accumulation process, the researchers were able to prevent both the buildup of mast cells and collagen in the breast. And that significantly reduced tumor spread to the lungs.

Based on these results, the team took a close look at tissue samples taken from human patients with hormone receptor-positive breast cancer. Like the mice, these patients had higher numbers of mast cells and increased deposits of collagen in their breasts. And these higher numbers correlated with the patients’ risk for breast cancer recurrence.

“We show gut commensal dysbiosis, an unhealthy and inflammatory gut microbiome, systemically changes the mammary tissues of mice that do not have cancer,” says Dr. Melanie Rutkowski of the UVA Cancer Center and the University of Virginia School of Medicine, who has pioneered research into the relationship between gut health and breast cancer.

“The tissue changes enhance infiltration of mast cells that, in the presence of a tumor, facilitate breast tumor metastasis,” Rutkowski says. “Mast cells recruited into the tissue environment during dysbiosis restructure the tissue architecture in such a way that tumor cells metastasize to other organs.”

These findings could help scientists develop ways to keep breast cancer from spreading to other parts of the body. This type of metastatic breast cancer often proves deadly; only 29 percent of women and 22 percent of men with metastatic breast cancer survive five years.

The study results could also allow doctors to predict which patients are at the highest risk of post-treatment cancer recurrence, enabling them to adjust the treatment strategy to prevent metastatic disease.

Keeping your gut and breast healthy

Judging from these results, maintaining the health of your gut microbiome is just as important as keeping your breast microbiome balanced in lowering your odds of developing aggressive breast cancer. Both these collections of microbes can be disrupted by poor diet, long-term antibiotic use and obesity, among other factors.

Luckily, many of the ways to maintain good gut microbiome health also take care of your breast microbiome. For instance, probiotics can play a crucial role in helping to balance the microbiomes in your gut and breast. If you don’t get enough of probiotic-rich foods like yogurt, kefir and sauerkraut, it’s important to add a daily probiotic supplement to your health regimen.

In addition, the Mediterranean diet has been found to support good gut and breast health. Many of the foods in the Mediterranean diet, like whole grains, fish, fruits and vegetables, nuts and red wine all support inflammation-lowering bacteria in the gut. And one study showed monkeys fed a Mediterranean diet had ten times more Lactobacillus in their breast tissue than those fed other diets, as well as higher levels of compounds shown to decrease breast cancer risk.

Sources:

Unhealthy Gut Helps Breast Cancer Spread, Research Reveals — UVAHealth

Reciprocal Interactions Between the Gut Microbiome and Mammary Tissue Mast Cells Promote Metastatic Dissemination of HR⁺ Breast Tumors — Cancer Immunology Research

The Link Between Gut Health and Breast Cancer — WebMD