Breast cancer is most treatable before it spreads beyond the breast. Once cancer cells travel to distant organs such as the lungs, bones, or liver, the disease becomes much harder to control.
Scientists around the world are searching for the hidden factors that allow cancer cells to spread. A new study from the University of Virginia Comprehensive Cancer Center points to an unexpected player: the bacteria living inside the gut.
The research, published in Nature Communications, shows that an unhealthy gut microbiome may increase the spread of hormone receptor-positive breast cancer by changing the body’s bile acids. These acids are best known for helping digest fatty foods, but they also act as signaling molecules that affect inflammation, metabolism, and immune responses throughout the body.
Normally, beneficial gut bacteria help keep bile acids in balance. When these bacteria are lost because of gut dysbiosis, the balance changes. The UVA researchers discovered that harmful bile acid changes can create an inflammatory environment that makes it easier for breast cancer cells to leave the original tumor and establish new tumors elsewhere in the body.
To investigate this process, the scientists studied laboratory mice with hormone receptor-positive breast cancer. They found that abnormal bile acid levels promoted inflammation in breast tissue and greatly increased the likelihood that cancer cells would spread to the lungs. This provided a clear biological pathway linking gut health to cancer metastasis.
The researchers then looked at information from patients with the same type of breast cancer. They found that people with higher bile acid levels and insulin resistance generally had lower survival rates.
They also noticed an encouraging trend: patients with metastatic breast cancer who were already taking bile acid sequestrants for other medical conditions appeared to survive longer than expected. These medicines lower bile acid levels and have already been approved by the U.S. Food and Drug Administration for certain cholesterol and metabolic disorders.
The scientists caution that these patient observations do not prove the drugs prevented cancer progression. Other factors may have influenced the results. Carefully designed clinical trials will be needed before doctors can recommend bile acid sequestrants specifically for breast cancer treatment or prevention.
One of the most exciting aspects of the study is that it identifies several possible treatment strategies. Future therapies might involve restoring beneficial gut bacteria with targeted probiotics or other microbiome treatments, lowering harmful bile acids with existing medicines, or using bile acid measurements to identify patients at higher risk of metastatic disease.
This study represents an important step toward understanding how organs far away from a tumor can influence cancer progression. It also shows that the gut microbiome may become an important target in future cancer care.
Although much more research is needed before these findings change routine treatment, the discovery opens a promising new direction for preventing breast cancer from spreading.
Because some of the potential medicines are already approved for other conditions, researchers may be able to move toward human clinical trials more quickly if future studies continue to produce positive results.
If you care about breast cancer, please read studies about how eating patterns help ward off breast cancer, and soy and plant compounds may prevent breast cancer recurrence.
For more health information, please see recent studies about how your grocery list can help guard against caner, and a simple way to fight aging and cancer.
Source: University of Virginia.
