Intratumoral microbiota in colorectal cancer: roles, therapeutic potential, and challenges

BACKGROUND: Colorectal cancer (CRC) is a multifactorial disease characterized by disruptions in cellular and immune functions, influenced by genetic mutations, environmental factors, and infections. Recent studies have highlighted the intratumoral microbiota as a critical component of the tumor microenvironment (TME), with a significant role in CRC initiation, progression, and therapeutic response. While the gut microbiota's influence on CRC is well-established, the specific contribution of intratumoral microbiota remains inadequately explored. Emerging evidence suggests that intratumoral microbiota may promote cancer progression through inflammatory pathways, metabolic alterations, and resistance to chemotherapy. Conversely, certain microbial communities exhibit tumor-suppressive properties by modulating immune responses and inducing apoptosis in tumor cells. AIM OF REVIEW: This review aims to highlight the dual role of the intratumoral microbiota in CRC and explore the potential of microbial interventions such as probiotics, phage therapy, and fecal microbiota transplantation (FMT) in enhancing therapeutic outcomes. Furthermore, the review examines the potential of microbiota-targeted therapies to optimize cancer treatment strategies and stresses the need for personalized approaches based on microbial biomarkers. KEY SCIENTIFIC CONCEPTS OF REVIEW: Intratumoral microbiota, as emerging tumor components, has been identified in various solid tumors. The review emphasizes the mechanisms by which intratumoral microbiota mediate inflammation, metabolic alterations, and immune modulation in CRC. It highlights how certain intratumoral microbiota are associated with resistance or sensitivity to treatments, and how manipulating the microbiota could enhance immunotherapy efficacy. By integrating advancements in multi-omics and clinical research, targeting the intratumoral microbiota represents a promising avenue for improving CRC therapies and overcoming treatment resistance. The clinical application of the intratumoral microbiota has the potential to revolutionize the treatment of CRC, paving the way for novel therapeutic strategies in oncology.