Assessment of tumor burden and response to therapy in patients with colorectal cancer using a quantitative ctDNA test for methylated BCAT1/IKZF1

Failure of colorectal cancer (CRC) treatment is due to residual disease, and its timely identification is critical for patient survival. Detecting CRC‐associated mutations in patient circulating cell‐free DNA is confounded by tumor mutation heterogeneity, requiring primary tumor sequencing to identify relevant mutations. In this study, we assessed BCAT1 and IKZF1 methylation levels to quantify circulating tumor DNA (ctDNA) and investigated whether this method can be used to assess tumor burden and efficacy of therapy. In 175 patients with CRC who were ctDNA‐positive pretreatment, ctDNA levels were higher with advancing stage (P