You have read a lot about the gut microbiome. But you may not have known that the breast also has its own microbiome. This mix of microbes could equally have an important effect on health, according to a new study in Applied and Environmental Microbiology. The results showed that microbes in the breast, even in low amounts, may play a role in preventing or increasing breast cancer risk.

One in eight women are diagnosed with breast cancer in their lifetime. We know that many variables are associated with this risk including age, genetics and environmental factors. With this new growing body of research, bacteria may be considered as one of those environmental factors. We know that breast feeding, since the early 60’s has been associated with a lower risk of breast cancer. Recent work suggests that breast milk supports the growth of beneficial bacteria in the breasts.

According to immunologist Delphine Lee who studies breast cancer at the John Wayne Cancer Institute in Santa Monica California, “It isn’t surprising in and of itself that the breast harbors microbes” The breast is exposed to the environment through the nipple and ductal system. Lactation also lowers breast cancer risk through the release of Oxytocin which clears the ducts of inflammatory debris. Dry brushing and nipple stimulation can actually create a healthy epithelial lining in the ducts.

Gregor Reid, a professor of microbiology and immunology at Western University in Ontario was the senior author of a study that analyzed bacterial DNA in breast tissue samples of 58 women who were undergoing lumpectomies or mastectomies for either benign or cancerous tumors. He and the other researchers also looked at 23 healthy women who underwent breast reductions or enhancements.

Findings showed that women with breast cancer had higher levels of some types of bacteria, including Enterobacteriaceae, Staphylococcus and Bacillus. Women without cancer had higher levels of other bacteria types, such as Lactococcus and Streptococcus. What we don’t know is whether certain bacteria found near breast tumors are the cause of breast cancer or whether they just thrive in the tumor environment.

These long named bacterial species may not mean anything to you now, but it will later as upcoming research will be able to use a patient’s bacterial makeup as a biomarker for cancer screening or to develop probiotics for improving prognosis and treatment outcomes.

Reference: Sheikh, K. “The Breast has its Own Microbiome”. ScientificAmerican.com, Oct 2016. p. 21.

Breakell, D. “Reducing your Risk for Breast Cancer.” Wellcast.org. Keynote, June 2014.