Role of Fusobacterium nucleatum and KRAS Genotype in Colorectal Cancer Development

Fusobacterium nucleatum (Fn) and activating mutations in the Kirsten rat sarcoma viral oncogene homolog (KRAS) are increasingly recognised as synergistic drivers of colorectal cancer (CRC). Fn promotes tumorigenesis through several mechanisms, such as virulence factors including FadA and Fap2. KRAS mutations amplify proliferative and inflammatory signalling. This chapter explores how Fn enhances KRAS-driven oncogenic cascades and how KRAS-mutant epithelium fosters bacterial colonisation. We also examine KRAS as a prognostic biomarker and highlight emerging microbiome-targeted strategies. Understanding this microbial–genetic crosstalk provides a foundation for precision prevention and combined therapeutic approaches in CRC.