The human microbiome is composed of trillions of microorganisms (bacteria, viruses, fungi) living inside and outside the human body.
The risk of breast cancer and recurrence could be associated with the composition and function of the breast/gut microbiome.
Research shows that there are different bacteria in the breast tissue of healthy women vs those with breast cancer and that the breast microbiome in women with cancer is different from that of women with benign disease, indicating that certain bacteria may be associated with breast cancer development and different responses to treatment.  Diet, drugs, toxins, lack of sleep, inactivity, and stress can negatively change the human gut microbiome which can alter blood estrogen levels, estrogen metabolism, chronic inflammation, the local breast immune microenvironment and its influence on breast cancer recurrence and metastasis. http://ow.ly/2WwJ50BftoE http://ow.ly/OPbN50BftoC
You can increase your good gut bacteria and improve your gut and breast microbiome with:
A plant-based diet
No refined sugar, processed and fast foods
Diverse foods
Fermented foods
High Fiber - 20-30 grams/day
Fasting
Exercise
Stress reduction
Sleep - 7-9 hrs/night
Quality probiotics

Cancer survivors with chronic inflammation may have an elevated risk of recurrence.  Chronic inflammation is associated with increased risk of breast cancer recurrence as it increases estrogen and insulin levels in the body and promotes tumor growth and metastasis.  Inflammation is part of the body’s natural defense mechanism designed to heal injuries and defend the body against foreign invaders but when inflammation goes on too long or becomes chronic it can have damaging effects on health.  An association has been found between breast cancer recurrence and reduced overall survival and increased concentrations of inflammatory markers, such as CRP, a test that can be measured by a healthcare provider.  Inflammation is caused by obesity, bad gut bacteria, stress, a bad diet, alcohol, high blood sugar, toxins, food allergens & sensitivities, and poor sleep quality.
You can control cellular inflammation by eating a whole food, plant-based diet full of anti-inflammatory foods and spices such as cloves, ginger, rosemary, and turmeric, reducing stress, exercising, maintaining a healthy weight, controlling your blood sugar, and getting 7-9 hours of sleep each night.