The Association Between Gut Microbiome and Cachexia in Colorectal Cancer: A Systematic Review

Area of Science:

• Microbiome research
• Cancer biology
• Gastroenterology

Background:

• Colorectal cancer (CRC) is often complicated by cachexia, a wasting syndrome characterized by muscle and fat loss.
• Cachexia significantly worsens patient survival and treatment outcomes in CRC.
• The gut microbiome's contribution to CRC cachexia is suspected but not well understood.

Purpose of the Study:

• To systematically review and synthesize existing evidence on microbial signatures associated with cachexia in colorectal cancer.
• To identify specific gut bacteria or microbial patterns linked to the hallmarks of CRC cachexia.

Main Methods:

• Systematic literature search of PubMed, Web of Science, and Scopus following PRISMA guidelines.
• Inclusion of preclinical (murine models) and clinical studies comparing microbiota in cachectic versus non-cachectic CRC patients.
• Quality assessment of included studies using the Newcastle-Ottawa Scale and CAMARADES checklist.

Main Results:

• Fifteen studies (13 preclinical, 2 clinical) met inclusion criteria, with moderate to high study quality.
• Preclinical models showed reduced microbial diversity, depleted butyrate producers, and enriched pathobionts (e.g., Enterobacteriaceae).
• Limited clinical data suggested associations between specific bacteria (e.g., *Fusobacterium nucleatum*) and cachexia onset.

Conclusions:

• Evidence suggests a link between gut microbiome alterations and colorectal cancer-associated cachexia.
• Causality, the direction of the relationship, and the clinical significance of these microbial changes require further investigation.
• The findings highlight the potential role of the gut microbiome in CRC cachexia pathogenesis.