Role of the Gut Microbiome in the Pathogenesis of Early-Onset Colorectal Cancer: Evidence and Perspectives

Abstract

The incidence of early-onset colorectal cancer (EO-CRC) has risen alarmingly, contrasting with the declining rates of colorectal cancer in older populations. Alterations in the gut microbiome have been implicated in the pathogenesis of this condition. The microbiome comprises a diverse community of microorganisms that inhabit the human body, primarily in the gastrointestinal tract, skin, and other mucosal surfaces. Over time, these microbial populations have developed a symbiotic relationship with their host, contributing to metabolism and immune regulation functions. Environmental factors, including diet, sedentary lifestyle, smoking, and alcohol consumption, influence the composition and function of the gut microbiome. These exposures can induce dysbiosis, which has been associated with an increased risk of EO-CRC. Evidence suggests that genetic ancestry or individual single-nucleotide polymorphisms have a minimal influence on the gut microbiome. Instead, environmental exposures appear to be predominant in its shaping.  Consequently, the pathogenesis of EO-CRC likely reflects a complex interplay between
environmental exposures, lifestyle-related factors, and host susceptibility. This review aims to summarize the current evidence of the role of the gut microbiome in EO-CRC pathogenesis and will explore future perspectives in this rapidly evolving field.