Circulating Tumour DNA and Risk-Stratified Surveillance Strategies for Patients with Colorectal Liver Metastases

As treatment approaches continue to diversify and novel therapies are on the horizon, more precise biomarkers are needed to guide treatment and sequencing decisions for patients with colorectal liver metastases (CLM). Clinicopathologic data traditionally used to stratify patient prognosis is imprecise when ascertaining a patient’s risk for recurrence and survival following hepatectomy for CLM. Circulating tumor DNA (ctDNA) is a novel option as both a biomarker for treatment response and as a “liquid biopsy” in some circumstances, and has been associated with outcomes if detected after completion of definitive therapy for colorectal cancer (CRC). Further, CLM somatic genomic profiling is critical for the understanding of individual patient’s tumor biology, and specific somatic mutations are associated with post-hepatectomy recurrence and survival. Current recommended surveillance guidelines following hepatectomy for CLM are generalized, and thus the incorporation of individual somatic mutations such as RAS allows for a more personalized, risk-stratified approach to postoperative surveillance for recurrent disease. In this chapter, the current evidence and future directions for the incorporation of ctDNA into treatment decisions will be discussed, as well as a novel surveillance pathway risk-stratified for recurrence based upon RAS mutations will be proposed.