The primary aims of this study were to investigate whether quantitation of ctDNA levels by measuring the amount of methylated BCAT1 and IKZF1 DNA using a real‐time PCR assay reflects burden of CRC at diagnosis and whether changes in the amount of methylated BCAT1/IKZF1 in blood accurately reflect response to different types of treatment. Here, BCAT1 is linked to colorectal carcinoma.