The cfDNA concentration was significantly correlated with the levels of clinical markers, especially CEA (P < 0.0001, Pearson r = 0.81), LDH (P < 0.0001, Pearson r = 0.84) and the sum of tumor diameters (P < 0.0001, Pearson r = 0.80). Here, CEACAM5 is linked to neoplasm.