Liquid Biopsy

Liquid biopsy is an emerging technique with the potential promise of enabling noninvasive characterization of cancer, as well as monitoring for early detection of recurrent disease. The term “liquid biopsy,” can refer to the detection of circulating tumor elements, including circulating tumor DNA (ctDNA). Interest in the role of ctDNA in colorectal cancer has been growing rapidly, as it may allow for early detection prior to clinical presentation or radiographic evidence of disease, identification of minimal residual disease (MRD) following curative-intent resection of locoregional disease, earlier detection of recurrent disease, or monitoring of treatment response in the neoadjuvant or metastatic setting. The focus of this chapter will be on the role of ctDNA as a measure of disease burden and treatment response in patients with colorectal liver metastases, particularly as it pertains to the selection of patients who might be optimal candidates for resection with curative intent.