Biomarkers Beyond Colonoscopy: A Review of Stool and Blood Tools for Colorectal Cancer Management

Abstract

ABSTRACT Colonoscopy remains the gold standard for colorectal cancer (CRC) detection, but its invasiveness, cost, and limited accessibility highlight the need for non-invasive biomarkers. To evaluate stool- and blood-based biomarkers as tools for CRC screening, surveillance, and disease monitoring, comparing their diagnostic accuracy, clinical utility, and limitations. A narrative review of recent evidence (2014–2024) on stool (FIT, multitarget DNA) and blood-based biomarkers (SEPT9, circulating tumour DNA, multi-analyte assays) was conducted, focusing on sensitivity, specificity, and real-world application. FIT demonstrates high specificity but modest sensitivity for advanced adenomas. Multitarget stool DNA improves sensitivity for CRC but at the expense of specificity. Blood-based assays, including SEPT9 methylation and ctDNA, show utility in non-invasive detection, minimal residual disease monitoring, and relapse prediction. However, challenges include cost, variability across populations, and infrastructural requirements. Stool- and blood-based biomarkers represent valuable adjuncts to colonoscopy, offering scalable, patient-friendly options for CRC management. Future directions include multi-omics platforms, artificial intelligence integration, and strategies to enhance accessibility in low-resource settings.