Although there is increasing utilization of ctDNA for precision oncology, there are still few studies systematically comparing the overall agreement of ctDNA findings with those of tumor tissue.12,38 It has also been especially unclear whether ctDNA can effectively detect copy number changes.39 Here we demonstrate that ERBB2 amplification was detectable in 69% of patients with ERBB2-amplified CRC. The gene discussed is ERBB2; the disease is colorectal carcinoma.