The Microbiome: A New Frontier in Overcoming Drug Resistance in Breast Cancer

The gut microbiome comprises bacteria, fungi, viruses, archaea, and their genetic materials. The gut microbiome influences the physiological and immunological functions of the body. When there is a change in the composition of microbiota in the gut, this is called dysbiosis. Dysbiosis is linked with several gastrointestinal and extra-gastrointestinal diseases, including some cases of breast cancer (BC). Molecular Subtype and stage of diagnosis both affect the way patients with BC are managed. BC is a heterogeneous disease and, in some cases, the response to treatment may not be as predicted. Dysbiosis of the gut and breast microbiota may influence the progression of BC and its response to treatment. Furthermore, treatment of BC may also alter the microbiota, leading to dysbiosis. This chapter reviews the relationship between dysbiosis and BC. Furthermore, how dysbiosis can be manipulated to improve tumor response or reverse resistance to drug treatment is also elaborated on.