Yes, the breast tissue contains a diverse array of bacteria and their genetic material that together represents its microbiome. It is part of the greater Holobiont which views the human body and its microbes as one symbiotic, functional entity. Trillions of bacteria reside and play an active role in our health.
The finding that breast tissue has its own unique microbiome is a recent discovery. The new research was published by a group of Canadian scientists in August 2016. They showed that breast bacterial profiles differed between normal adjacent tissue from women with breast cancer and tissue from healthy women. Women with breast cancer had higher amounts of bacteria in their breast microbiome that had the ability to cause DNA damage in vitro and furthermore they had less of some bacteria that are known for their beneficial anti- carcinogenic effects.
Although researchers are far from certain if specific microbes or chemicals made by our microbial friends might influence breast cancer, lessons learned in relation to beneficial bacteria and other body sites - the gut for example, indicate that they probably operate through the immune system. Multiple studies show that microbes exert their beneficial, and sometimes not so beneficial, properties via manipulating the immune system. It is possible that certain aspects of the environment and genetics might interact to influence microbial growth on breast tissue. The challenge for researchers is to find out what causes changes to microbes residing on breast tissue.
For now, there are more questions than answers. But that is where some of the greatest scientific breakthroughs have been made. By staring down puzzling questions and looking at them from different angles. Scientists will now move to study the breast microbiome with vigor. With each small discovery in the realm of breast cancer, the odds of prevention and treatment are better. We are learning that our internal ecosystems matter more than ever, that we must harness what we know about lifestyle factors that will influence our microbiome for the better- such as diet, not smoking, stress resiliency, spending time in nature, pre and probiotics, and fermented foods.