Among these four patients, two of them (patient 1 and patient 2) have CEA (carcinoembryonic antigen) values less than 5 ng/ml, as revealed in the following serum tumor biomarker examinations, and these two patients are classified as 5-FU-benefit, while the other two patients (patient 3 and patient 4) with CEA values over 5 ng/ml (abnormal values), are classified as 5-FU-futile (Figure 8A). The gene discussed is CEACAM5; the disease is neoplasm.