CEACAM5 and metastatic neoplasm: Measurement of CEA levels exerted a low sensitivity in identifying disease recurrence, with only 3 patients (20.0%) having elevated CEA levels at the first sign of confirmed relapse: 1 patient with metastatic disease in the lung only was identified first by CEA levels and subsequently by imaging and pathological confirmation, with persistently negative ctDNA findings; 1 patient with metastatic disease involving multiple organs had concurrent imaging and ctDNA findings of recurrence; and 1 patient had concurrent ctDNA positivity and subsequent radiographic confirmation.