Integrated molecular, epigenetic, microbial and liquid biopsy biomarkers in colorectal cancer: implications for prognosis and precision therapy

Abstract

Abstract Background Colorectal cancer (CRC) is a biologically diverse malignancy driven by a complex interplay of genetic mutations, epigenetic changes, tumour microenvironmental factors and host–microbial interactions. Foundational molecular events including APC-associated Wnt/β-catenin dysregulation, TP53 inactivation, KRAS and BRAF mutations and aberrant PI3K/AKT signalling due to PIK3CA and PTEN alterations, contribute significantly to disease initiation, progression and therapeutic resistance. Microsatellite instability (MSI), arising from defective DNA mismatch repair, defines a distinct subset of CRC with characteristic biological and therapeutic behaviour. Objective This review critically evaluates established and emerging molecular biomarkers for CRC, highlighting their mechanistic significance and translational relevance in the evolving precision oncology landscape. Methods A comprehensive narrative evaluation of the literature was conducted, focusing on pathways regulating oncogenes, regulatory microRNAs, gut microbiota dysbiosis and liquid biopsy approaches, particularly circulating tumour cells (CTCs) and circulating free DNA (cfDNA). Results Core molecular alterations remain central to CRC pathogenesis and influence treatment responsiveness. Increasing evidence also supports the role of microRNA dysregulation and microbiome imbalance in modulating tumour progression and immune escape. Liquid biopsy technologies offer minimally invasive, real-time assessment of tumour development. Discussion An integrated understanding of molecular drivers and emerging biomarker platforms is essential for advancing personalized CRC management. Graphical abstractDiagram of colorectal cancer highlighting tumor location, gender incidence, microbiota, pathogenesis, and key biomarkers.The figure presents a comprehensive overview of colorectal cancer (CRC) with a labeled diagram showing the colon and a tumor. An arrow indicates a higher incidence in women with corresponding gender icons. Below, microbiota is depicted, connecting to "Pathogenesis," which leads to diagrams of left and right-sided colons. At the bottom, seven biomarkers for CRC, including BRAF, KRAS, miRNA, MSI, APC Gene, TP53 Gene, and PI3KEA, are shown in horizontal boxes, highlighting critical elements associated with the disease.