Notable progress has been made in the field of circulating tumour DNA (ctDNA) analysis over the past decade. Along the spectrum of promising clinical applications of ctDNA across the various stages of cancer, blood-based genotyping in advanced cancer to guide targeted therapies, and more recently, molecular residual disease detection to improve patient selection for adjuvant therapy in stage II colon cancer, are the only indications with sufficient evidence to be integrated into routine clinical care.