Recent research indicates that a person’s gut health might influence the spread of breast cancer to other body parts. The study, conducted by the University of Virginia Comprehensive Cancer Center under Melanie Rutkowski, Ph.D., highlights how an unhealthy buildup of bile acids in the gut may promote breast cancer metastasis. This discovery could pave the way for preventive strategies against cancer spread.
Gut Microbiome and Cancer Spread
Rutkowski explained to Newsweek that an unbalanced gut microbiome disrupts bile acid regulation. These acids are potent signaling molecules, and their imbalance can disturb both metabolism and immune functions. This disruption fosters an environment conducive to hormone receptor-positive (HR+) breast cancer spread, the commonest form of metastatic breast cancer.
Impact of Hormone Receptor-Positive Breast Cancer
Hormone receptors in cells are activated by hormone binding, which can promote cancer growth. According to the Breast Cancer Research Foundation, around 80% of breast cancers are HR+. With approximately 225,000 annual HR+ breast cancer diagnoses in American women, metastasis complicates treatment and raises mortality risks.
Potential Treatment Avenues
Rutkowski suggests modifying bile acid composition or using bile acid sequestrants to mitigate metastasis risks. These medications are already FDA-approved for metabolic diseases. The research underscores the connection between gut microbiome imbalances and the metastasis driven by bile acids, presenting new possibilities for identifying high-risk patients and potential treatment approaches.
Co-author Audrey Putelo, Ph.D., emphasized that since bile acids can be both measured and modified, new methods could emerge to reduce metastatic disease risks. The study found elevated bile acids and insulin resistance linked to lower survival rates in HR+ breast cancer patients. However, those receiving bile acid-suppression therapy seemed to live longer. Further research is necessary to confirm these drugs’ direct benefits.
Future Research Directions
Rutkowski described the results as promising. The team is investigating whether FDA-approved drugs can prevent initial cancer spread. The research aims to assess the impact of long-term drug use on preventing breast tumor spread. Additionally, since stable microbiome modification techniques remain underdeveloped, the team seeks to understand bile acid signaling’s immune-related effects in tissues where breast cancers typically metastasize. Identifying these targets could help reduce breast tumor spread.
Reference: Putelo, A. M., Bajgai, S., Poblete, M. K., Guido G., Lanfranca, M. P., Rutkowski. M. R.; et al. Commensal Dysbiosis Alters Primary Bile Acid Signaling to Drive Mammary Gland Inflammation and Breast Tumor Dissemination. Cancer Res 2026; https://doi.org/10.1158/0008-5472.CAN-25-4466
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