Gut Microbes: Role in Cancer and Cancer Drug Resistance

The gut microbiota is becoming more and more of a research area in many diseases, including cancer, obesity, diabetes, brain disease, rheumatoid arthritis, and cardiovascular disease. The human digestive tract contains about 100 trillion microorganisms. Cancer is the most prevalent malignancy in the world. The likelihood of survival can be increased by an accurate, early diagnosis and the necessary medical care. Recent studies have demonstrated that the microbiome has an impact on cancer. Different microbial signatures with various patterns have been found in the cancer, depending on the stage and biological subgroups. In cancer, the gut microbiota has been shown to modulate the efficacy of anticancer drugs. The changed gut microbiota is linked to resistance to immunological checkpoint inhibitors (ICIs) and chemotherapy treatments, whereas the addition of certain species of bacteria can restore the responsiveness to anticancer medications. Various evidence suggested the potential of gut microbiota manipulation to increase the effectiveness of anticancer medications. In this book chapter, we focused on the gut microbiota population and its relationship to cancer therapy resistance, with a particular emphasis on its potential to serve as a biomarker for the disease. Despite the important results from preclinical models and patient clinical data, a deeper comprehension of the interactions between microbiota and cancer therapy aids in the identification of novel strategies for cancer prevention, the stratification of patients for more effective treatment, and the reduction of treatment complications.