In a study from the University of Virginia, scientists found an unhealthy gut triggers changes in normal breast tissue that helps breast cancer spread to other parts of the body.
The gut microbiome—the collection of microbes that naturally live inside us—can be disrupted by poor diet, long-term antibiotic use, obesity, or other factors.
The team found when this happens, the ailing microbiome reprograms important immune cells in healthy breast tissue, called mast cells, to facilitate cancer’s spread.
The finding could help scientists develop ways to keep breast cancer from metastasizing (spreading to other parts of the body).
When it does, it is often deadly: Only 29% of women with metastatic breast cancer survive five years; for men with metastatic breast cancer, that figure is just 22%.
The team says the discovery could also let doctors predict which patients are at the greatest risk of cancer recurrence after treatment.
The researchers’ latest work reveals complex interactions between our gut microbes and mast cells in the breast. Mast cells are blood cells that help regulate the body’s immune response to disease and allergens.
The new work suggests that the gut microbiome can systemically influence mast cell behavior and function in the presence of tumors.
The team found that an unhealthy microbiome caused the mast cells to accumulate in the breast.
These changes continued after tumor formation in a mouse model of hormone receptor-positive breast cancer, making the breast tissue a prime launching ground for cancer’s incursions into other parts of the body.
Further, the scientists found that the mast cells increased the amount of collagen in the mice’s breast tissue and spurred earlier cancer spread.
Blocking the process that led to mast-cell accumulation prevented both, significantly reducing tumor spread to the lungs.
The researchers also examined tissue samples taken from human patients with hormone receptor-positive breast cancer.
They found these patients, like the mice, had increased numbers of mast cells and increased deposits of collagen.
The number of mast cells correlated with the amount of collagen and, notably, the patient’s risk for a recurrence of breast cancer.
If you care about cancer, please read studies that a low-fat diet could help improve survival in breast cancer, and what you need to know about cancer and booster shot.
For more information about cancer, please see recent studies about new ways to increase the longevity of cancer survivors, and results showing vitamin D could benefit men with advanced cancer.
The study was conducted by Melanie R. Rutkowski et al and published in Cancer Immunology Research.
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