Gut Microbiota and Breast Cancer: The Dual Role of Microbes

SIMPLE SUMMARY: The set of microbes in our body, called microbiota, exerts a wide variety of beneficial effects and is related to the state of health of the person. An alteration in the composition of the microbiota is called dysbiosis and is related to the state of the disease. Microbiota exists in many locations in our body, but the most important from a quantitative point of view is the intestinal microbiota, which is why it is the most studied. However, our microbiota is also capable of producing harmful effects, thereby in recent years it has been considered another environmental factor to be taken into account in the risk of developing diseases, including cancer. ABSTRACT: Breast cancer is the most frequently diagnosed cancer and also one of the leading causes of mortality among women. The genetic and environmental factors known to date do not fully explain the risk of developing this disease. In recent years, numerous studies have highlighted the dual role of the gut microbiota in the preservation of host health and in the development of different pathologies, cancer among them. Our gut microbiota is capable of producing metabolites that protect host homeostasis but can also produce molecules with deleterious effects, which, in turn, may trigger inflammation and carcinogenesis, and even affect immunotherapy. The purpose of this review is to describe the mechanisms by which the gut microbiota may cause cancer in general, and breast cancer in particular, and to compile clinical trials that address alterations or changes in the microbiota of women with breast cancer.