CEACAM5 and neoplasm: For patients with a tumor size < 1 cm, serum CEA levels < 5 ng/mL, and C/T ratio < 0.5, the avoidance of standard lobectomy or lymph node dissection may be justified, and a less invasive procedure, such as sublobar resection with nodal sampling or even without lymphadenectomy, may be an alternative approach.