The bidirectional relationship between gut microbiota and the development of colorectal cancer

Background As a core component of the human intestinal microecosystem, the gut microbiota has been increasingly recognized for its pivotal role in colorectal cancer (CRC), a globally prevalent malignancy with rising incidence and mortality rates. The association between intestinal microecological imbalance and CRC has emerged as a key research focus in recent years. Methods This narrative review summarizes the latest literature (up to June 2026) on the bidirectional regulation between gut microbiota and CRC progression. The review describes how microbial dysbiosis is associated with CRC progression through multiple molecular and metabolic pathways. It also discusses how tumor-induced microenvironmental alterations reshape the gut microbiota, potentially establishing a detrimental feedback loop. Results The study explores how dysbiosis of the gut microbiota can induce and promote the progression of CRC through multiple pathways. Conversely, it demonstrates how alterations in the intestinal microenvironment during CRC development reshape the composition of the gut microbiota, thereby creating a vicious cycle. Conclusion The gut microbiota shows promise as a potential target for colorectal cancer screening, diagnosis, and therapy. However, substantial validation and standardization efforts are still required before its clinical application.