Blood-based biomarkers for diagnosis, prognosis and treatment of colorectal cancer

The global burden of colorectal cancer (CRC)-associated morbidity and mortality is increasing, in part due to a lack of early detection. Direct structural examination techniques, such as colonoscopy, are invasive and can therefore affect the willingness of patients to participate in screening. Recently, the use of "liquid biopsy" has gained considerable attention as a novel source of biomarkers. Blood-based biomarkers could prove to be practical tools for CRC detection, as the monitoring of biomarkers in biological fluids offers many advantages, including minimal invasiveness and easy accessibility. Biomarkers with high specificity and sensitivity can enable the detection of CRC at an early stage, thereby improving prognosis, prediction of treatment response, and recurrence risk. In this review, we summarize that the biomarkers currently thought to have potential for the early detection and monitoring of CRC, including circulating tumor cells, DNA, RNA and proteins.