State of omics-based microbial diagnostics of CRC.

Colorectal cancer (CRC) remains a major burden of cancer-related morbidity and mortality globally, especially when detected at later stages. Early detection through improved and more accessible diagnostics is critical for reducing the severity of CRC. As our understanding of CRC and the microbial inhabitants of the gastrointestinal tract continues to improve, it has become increasingly recognized that the bacterial component of the gut microbiome may provide diagnostic utility for detecting CRC. This is because CRC is often accompanied by shifts in bacterial taxa, and the metabolites produced or utilized by the CRC-associated gut bacterial community. Advances in sequencing and metabolite profiling technologies paired with our growing understanding of CRC-associated microbial taxa, present an opportunity for new gut microbiome-based diagnostics. In this narrative review, we discuss bacterial taxa and gut metabolites that have been investigated as predictive features for CRC diagnosis. We aim to highlight the tremendous progress that has been made in identifying gut microbiome-based features and why they should be further explored as potential CRC diagnostics. We also identify challenges that future work must address, including the impact of patient lifestyle, variation in methodology, and nonstandard data management practices. Resolving these areas of study design and implementation is key to understanding the complex bacterial communities and their by-products associated with CRC, and the development of microbial diagnostics that can detect them.