Objective:

To review the pathogenic mechanisms and taxonomic identification of Fusobacterium nucleatum (Fn) in colorectal cancer (CRC) and discuss advancements toward clinical diagnostics.

Approach:

• Mechanistic Analysis: Examined Fn's role in activating NF-κB and Wnt/β-catenin pathways, modulating the immune microenvironment, and influencing metabolic reprogramming and epigenetic regulation.
• Technological Advances: Discussed the transition from culture-based assays to high-resolution technologies like in-situ hybridization, quantitative PCR, and next-generation sequencing.
• Taxonomic Clarification: Reviewed recent genomic advancements that have refined the classification of Fn subspecies and their implications for CRC pathogenesis.

Key Findings:

• Fn is implicated in CRC through mechanisms such as activation of NF-κB and Wnt/β-catenin pathways, immune modulation, and metabolic reprogramming.
• Recent genomic studies have clarified the distinct identities of Fn subspecies, with F. animalis linked to adverse clinical outcomes in CRC.
• High-resolution detection technologies enable species- and subspecies-level quantification of Fn, paving the way for noninvasive diagnostic markers.

Interpretation:

The review highlights the complex role of Fn in CRC and the need for standardized diagnostic approaches.

Limitations:

• Current studies face challenges related to subspecies heterogeneity and non-standardized diagnostic platforms.
• Confounding factors such as oral hygiene and concurrent microbial infections may influence the association between Fn and CRC.

Conclusion:

Advancements in understanding Fn's role and detection may lead to improved diagnostic strategies for CRC.