Although collecting blood specimens only requires minimally invasive procedures and space occupancy without any radiation exposure, conventional serum biomarkers, such as CEA and CYFRA21-1, are not optimal especially for detecting early-stage cancer because of their low sensitivity and cancer stage-dependent differences (Rastel et al. 1994; Pujol et al. 1996; Bombardieri et al. 1994; Urabe et al. 2020; Molina et al. 1994). The gene discussed is CEACAM5; the disease is cancer.