Many factors, including thoracoscopic surgery [9], carcinoembryonic antigen (CEA) [10], standard uptake value on 18-fluorodeoxyglucose positron emission tomography [11], large tumor size [12], and lymph/vascular and/or pleural invasion [13] have been reported to be associated with occult hilar or mediastinal LN metastases, even in clinically diagnosed early-staged NSCLC. The gene discussed is CEACAM5; the disease is neoplasm.