Specifc microbiome patterns and their association with breast cancer: the intestinal microbiota as a potential biomarker and therapeutic strategy

Abstract

Abstract Breast cancer (BC) is one of the most diagnosed cancers in women. Based on histological characteristics, they are classifed as non-invasive, or in situ (tumors located within the milk ducts or milk lobules) and invasive. BC may develop from in situ carcinomas over time. Determining prognosis and predicting response to treatment are essential tools to manage this disease and reduce its incidence and mortality, as well as to promote personalized therapy for patients. However, over half of the cases are not associated with known risk factors. In addition, some patients develop resistance to treatment and relapse. Therefore, it is necessary to identify new biomarkers and treatment strategies that improve existing therapies. In this regard, the role of the microbiome is being researched as it could play a role in carcinogenesis and the efcacy of BC therapies. This review aims to describe specifc microbiome patterns associated with BC. For this, a literature search was carried out in PubMed database using the MeSH terms “Breast Neoplasms” and “Gastrointestinal Microbiome”, including 29 publications. Most of the studies have focused on characterizing the gut or breast tissue microbiome of the patients. Likewise, studies in animal models and in vitro that investigated the impact of gut microbiota (GM) on BC treatments and the efects of the microbiome on tumor cells were included. Based on the results of the included articles, BC could be associated with an imbalance in the GM. This imbalance varied depending on molecular type, stage and grade of cancer, menopause, menarche, body mass index, and physical activity. However, a specifc microbial profle could not be identifed as a biomarker. On the other hand, some studies suggest that the GM may infuence the efcacy of BC therapies. In addition, some microorganisms and bacterial metabolites could improve the efects of therapies or infuence tumor development.