Epigenetics, Microbiota, and Breast Cancer: A Systematic Review.

Breast cancer is the most frequently diagnosed cancer in women worldwide. According to recent studies, alterations in the microbiota and epigenetic modulations are risk factors for this disease. This systematic review aims to determine the possible associations between the intestinal and mammary microbial populations, epigenetic modifications, and breast cancer. To achieve this objective, we conducted a literature search in the PubMed, Web of Science, and Science Direct databases following the PRISMA guidelines. Although no results are yet available in humans, studies in mice suggest a protective effect of maternal dietary interventions with bioactive compounds on the development of breast tumors in offspring. These dietary interventions also modified the gut microbiota, increasing the relative abundance of short-chain fatty acid-producing taxa and preventing mammary carcinogenesis. In addition, short-chain fatty acids produced by the microbiota act as epigenetic modulators. Furthermore, some authors indicate that stress alters the gut microbiota, promoting breast tumor growth through epigenetic and gene expression changes in the breast tumor microenvironment. Taken together, these findings show the ability of epigenetic modifications and alterations of the microbiota associated with environmental factors to modulate the development, aggressiveness, and progression of breast cancer.