Furthermore, in the group that included patients with lymph node metastasis (n = 34), the sensitivity of ctDNA, CEA and combination of both ctDNA and CEA were 73.5% (25/34), 76.5% (26/34) and 85.3% (29/34), respectively. This evidence concerns the gene CEACAM5 and metastatic malignant neoplasm in the lymph nodes.