Two ideas often center stage in the medical discourse of today: “microbiome” and “cancer”. The human body is host to a vast and intricate group of microorganisms collectively known as the microbiome. These microorganisms (bacteria, viruses, fungi, and archaea) reside in various parts of the body such as the mouth, gut, skin, and respiratory tract (Hou, Wu, & Chen, 2022). The term “microbiome” captures not only the diversity and count of bacterial species but also their functional ability and interactions with the human host, therefore includes the genetic material of all these organisms (Berg, Rybakova, & Fischer, 2020). The concept of the microbiome has evolved drastically with time. Early microbe observations go back to the 17th century with the debut of the microscope; yet the full complexity and impact of the human microbiome did not become obvious until the late 20th and early 21st centuries with the development of sophisticated sequencing technology (Sidebottom, 2023). Starting the Human Microbiome Project (HMP) in 2007 under the direction of the National Institute of Health, it signified a sea change in microbiome research (NIH HMP Working Group, Peterson, Garges, & Giovanni, 2009). This effort aimed to identify and characterize the microorganisms in both normal and diseased people. This has facilitated in elucidating the role of the microbiome in human health. The human microbiome is fundamental for many physiological processes including pathogen protection, metabolic activity, immune system control, and digestive health. Dysbiosis—an imbalance in the microbial population—has been related to several disease conditions including inflammatory bowel disease (IBD), cardiovascular disease, diabetes, obesity, and cancer (DeGruttola, Low, Mizoguchi, & Mizoguchi, 2016).

One of the most complex and multifaceted diseases known to exist, uncontrolled cell proliferation defines cancer and remains a major medical issue of great relevance today. While environmental and genetic factors have long been connected to cancer formation, emerging research suggests that the human microbiome could be a key determinant of carcinogenesis (Cooper, 2000). The diverse group of microorganisms in the gastrointestinal (GI) tract has attracted attention as it may affect cancer formation, course of action, and response to treatment (Liu et al., 2022). Research on gut bacteria has been extensive in relation to gastrointestinal malignancies—that is, those affecting the colon, stomach, and esophagus among other cancer forms. Knowing the intricate relationships between human physiology and gut bacterial communities is a seductive approach to look at novel therapeutic and preventive strategies for gastrointestinal cancers.