Fecal Microbiome Alterations in Colorectal Cancer: A Systematic Review of Compositional Changes and Microbial Biomarkers.

Colorectal cancer (CRC) is one of the most common types of cancer worldwide, and the gut microbiome plays a crucial role in its development. In the study, we examine the variation in gut microbial community composition among individuals diagnosed with CRC based on human fecal samples. A systematic search of online databases, including MEDLINE (PubMed), Web of Science, Embase, and Scopus up to March 2026, following the requirements outlined in the PRISMA guideline. The search strategy was based on a combination of keywords, including "colorectal cancer," "gut microbiome", and "feces." The study analyzed 43 research articles on colorectal cancer microbiome. Most investigations utilized culture-independent techniques, revealing variations in microbial profiles between colorectal cancer cases and healthy controls. Fusobacterium and Porphyromonas emerged as potential colorectal cancer biomarkers, while multi-bacteria predictive models showed promise in enhancing colorectal cancer detection sensitivity and specificity. In this review, we will explore how advanced sequencing techniques have the potential to complement current non-invasive methods for early diagnosis and prevention of colorectal cancer. This includes conducting studies with robust statistical power and consistent, replicable methodologies, taking into consideration host factors, and performing external validation of predictive models.