Any discussion on Women and cancer usually includes the role that Hormones, Estrogen and Progesterone, play in tumor initiation and growth. An excess of estrogens can over stimulate mammary tissues and turn cells pre-cancerous.
Recently, a new arena of influence was discovered, the Gut-Hormone relationship where intestinal bacteria groups influence estrogen levels and vice versa. Certain intestinal microbes produce an enzyme, beta-glucuronidase, that is capable of metabolizing estrogen. The group of microbes capable of acting on estrogens are called the Estrobolome. ref 
After estrogens work in the body, they are marked for colon elimination by the liver with a process that conjugates the estrogen to deactivate it. Once in the colon, this estrogen form can be acted upon by the estrobolome microbes and is de-conjugated which returns it to an active state that can get recycled back into the body.
This process increases the level of active estrogens in circulation. This can have an adverse effect on a number of conditons related to estrogen connected diseases. Normally, under healthy intestinal conditions, the estrobolome microbes are limited in numbers and do not prove to be a problem. But, when intestinal health is upset, known as gut dysbiosis, either from poor diet or other stressors, the estrobolome microbes also are upset and more estrogen may be recyled than the body can handle. Chronic diseases often result. Controlling beta-glucuronidase activity is paramount.
This new area of estrobolome research is very new. There is a little more science on the general microbiota of microbes in the intestinal tract. Some microbes get into the body too. Thus, one starts with the known and builds from there with new research. There are a number of articles on this website that deal with the know.
A priority should be to maintain a healthy gut bacteria presence. The pH or acid/alakline balance is important. see these Probiotics articles. article article